LED lamps including LED work lights

ABSTRACT

Work light has LEDs that may require heatsink. Desired radiation pattern achieved by using optical components designed to produce beam or LEDs may have beams in different directions. Radiation pattern of LEDs may be changed by refractive-reflective optics or by convex lenses. Convex lenses may be hemispheres, other planoconvex shapes, concavo-convex shapes, or other shapes. Curved surfaces on any lenses may be spherical or aspheric. Ballast to operate the LEDs from line voltage AC or low voltage DC. Work light may contain batteries. The work light may be mounted on a stand. May have accessory mount. May have charging station. May have a paging transmitter to activate a paging receiver in work light. May have openings for heat transfer from heatsink to ambient air external to light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S. PatentApplication Ser. No. 60/877,141 filed 24 Dec. 2006. The contents of theabove application and U.S. Patent Application Ser. No. 60/521,240 filed18 Mar. 2004, Application Ser. No. 60/521,680 filed 16 Jun. 2004,Application Ser. No. 60/521,689 filed 17 Jun. 2004, Application Ser. No.60/521,738 filed 28 Jun. 2004, and Application Ser. No. 60/521,888 filed17 Jul. 2004 under the title LED Work Light are hereby expresslyincorporated by reference into the detailed description hereof.

FIELD OF THE INVENTION

The application relates to work lights. More particularly it relates toLED work lights.

BACKGROUND OF THE INVENTION

Work lights, often known as “trouble lights”, are widely used inautomotive repair shops and other repair settings and constructionsettings. Such work lights are often in a form that can alternatively behandheld or hung from a suitable elevated object such as a raisedautomobile hood.

Incandescent work lights have been in use, but they have some drawbacks.One drawback is that work lights are all too often dropped or knockeddown and fall onto a hard surface, and this often results in breakage ofthe bulb or its filament. An additional drawback of incandescent worklights is a safety hazard that results from the possibility of the bulbbreaking with its hot filament in close proximity to flammable materialsuch as spilled flammable liquid if the work light suffers a fall.

Fluorescent work lights exist and they have advantages over incandescentwork lights, namely greater energy efficiency and a reduced hazard ofigniting flammable materials if they suffer a fall. However, fluorescentwork lights can experience breakage of their bulbs if they suffer afall. Although breakage of an operating fluorescent bulb is not aslikely to ignite nearby flammable materials as breakage of anincandescent bulb is, there is still a slight chance that a fluorescentbulb can ignite adjacent flammable materials if broken while operatingsince fluorescent lamps normally have hot filaments while they areoperating. There are fluorescent work lights that have impact cushioningmeans included to increase their ability to survive falls, but theystill have a slight chance of experiencing breakage of their bulbs ifthey fall onto a hard surface.

LED work lights are better able to survive falls than are work lightsthat have glass bulbs. Furthermore, LEDs do not generally operate withparts hot enough to ignite flammable materials, so even falls that doresult in breakage are less likely to cause fires than are similar fallsof work lights that have glass bulbs.

The prior art has LED work lights. Many produce light that isinsufficiently intense or in the form of an excessively narrow beam. Itis possible to achieve adequately intense light in an adequately widebeam by using a large number of LEDs. However, a work light having asufficient number of LEDs and sufficient power input to achieveadequately intense light in an adequately wide beam without overheatingof the LEDs is generally large and expensive.

As described further herein some features of some aspects of theinvention will address some of the issues raised above. Other featuresand other aspects will address other issues with existing LED lights toprovide alternatives or improvements thereto.

SUMMARY OF THE INVENTION

In a first aspect the invention provides an LED work light a light head,at least one light emitting diode (LED) contained within the light head,and a handle that is attached to said light head. The light head emitslight external to the light head from light emitted by the at least one.LED. The at least one LED is of a high power type that normally requiresheatsinking. The light emitted from the work light is in the form of abeam that has a useful beam width of light adequate for use in workingfor prolonged periods is essentially at least 40 degrees wide andessentially no more than 90 degrees wide.

In a second aspect the invention provides a work light having a highpower LED that requires a heatsink for operation in a normal workingenvironment while preserving a useful life in prolonged use, an opticassociated with the LED such that a beam width of light radiating fromthe LED is changed by the optic, and light emitting from the optic has auseful beam width of light adequate for use in working for prolongedperiods, a heatsink for use with the LED to preserve useful working lifeof the LED when operated in prolonged use, a casing substantiallyenclosing the LED and optic, and the casing housing the heatsink, and atransparent cover in the casing through which the beam of light from theoptic can escape the casing along a beam axis.

In a third aspect the invention provides a work light having a highpower LED that requires a heatsink for operation in a normal workingenvironment while preserving a useful life in prolonged use, an opticassociated with the LED such that the optic creates a beam emitting fromthe optic for use in working for prolonged periods that has a moreuniform light density across its beam width than the light densityacross a beam emitted by the LED, a heatsink for use with the LED topreserve useful working life of the LED when operated in prolonged use,a casing substantially enclosing the LED and optic, and housing theheatsink, and a transparent cover in the casing through which the beamof light from the optic can escape the casing along a beam axis.

In a fourth aspect the invention provides a work light having a highpower LED that requires a heatsink for operation in a normal workingenvironment while preserving a useful life in prolonged use, an opticassociated with the LED such that a beam edge of light radiating fromthe LED is changed by the optic to produce a beam for use in working forprolonged periods wherein the beam edge has a different sharpness, aheatsink for use with the LED to preserve useful working life of the LEDwhen operated in prolonged use, a casing substantially enclosing the LEDand optic, and the casing housing the, and a transparent cover in thecasing through which the beam of light from the optic can escape thecasing along a beam axis.

The LEDs may be white LEDs. The work light may have one or moreheatsinks that assist in dissipating heat from the LEDs. One or moreoptical components may be included in order to achieve a beam width ofat least 40 degrees and no more than 90 degrees.

Optical pieces may be a molded plastic part wherein total internalreflection occurs. Each light emitting diode of the at least one lightemitting diode may produce a beam less than 40 degrees wide and the atleast one light emitting diode may be arranged to produce a combinedbeam that is at least 40 degrees wide.

The at least one light emitting diode may produce a beam that is morethan 90 degrees wide and the work light may have one optical componentfor each light emitting diode of the at least one light emitting diode,each optical component may be placed forward from its respective lightemitting diode in order for the work light to produce a beam that isessentially less than 90 degrees wide. At least one optical componentmay be a prism.

The work light may be able to work from low voltage direct current. Themay have a cavity for receiving a removable DC power source. The lighthead may have a casing that is plastic.

The work light may have one or more pieces of compressible material toprotect the work light from impacts. The impact protection material may,for example, be selected from rubber or a thermoplastic elastomer.

The optical component may be a convex lens. The convex lenses may bepart of a transparent lens assembly. The transparent lens assembly maybe molded. It may be machined after molding. It may be polished aftermachining.

Each convex lens may be planoconvex. Each planoconvex lens may beaspheric.

The removable DC power source may include rechargeable batteries. Theremovable DC power source may be an external power source with wireconductors. The work light may be able to be operated from essentially12 or 12-14 volts DC.

A kit may include a work light and a first removable DC power sourceincluding rechargeable batteries and a second removable DC power source.The second removable power source may include an external power sourcewith conductors for connection in the cavity. The first removable DCpower source and second removable DC power source may be interchangeablein the cavity.

The kit may include a charging base that can recharge the batteries. Thesecond removable DC power source may include an AC line voltage to lowvoltage DC transformer and a line voltage cord, the transformer betweenthe conductors for electrical connection to the cavity and the linevoltage cord.

The work light may include a paging receiver. The paging receiver may beused for locating the work light. The work light may have an alarm that,when activated, assists in locating the work light. The paging receivermay receive pages from an external device, such that the work lightcauses the alarm to activate upon receipt of a page by the pagingreceiver from the external device. The alarm may include activation ofthe light.

A kit may include a work light and a paging receiver and a charging basehaving a transmitter for transmitting pages to the paging receiver.

In a fifth aspect the invention provides a work light including at leastone LED and an LED mounting member to which the at least one LED ismounted, a heatsink thermally connected to at least one LED, a casingwithin which the LED assembly and heatsink are mounted. In this aspectthe casing has a transparent cover through which light emitting from theLED can escape the casing, and the casing has openings through whichheat from the heatsink may be transferred to ambient air external to thecasing to provide cooling for the heatsink.

The openings may be adjacent to the heatsink. The openings may bedimensioned to prevent accidental access through the casing to theheatsink.

A casing may be primarily made from of a rigid plastic. The casing maybe primarily comprised of an electrically insulative material.

The work light may include a hook mounted to the casing on aball-and-socket joint such that the hook can be rotated about 360degrees relative to the casing when in use, and may include a recess inthe casing such that the hook can be rotated on the ball-and-socketjoint to be received within the recess when not in use.

The work light may include a hook mounted to the casing on aball-and-socket joint such that the hook can be rotated about 360degrees relative to the casing when in use and such that the hook can berotated on the ball-and-socket joint to lay flat against the casing whennot in use.

The casing may have a recess against which the hook lays flat, therecess recessed sufficiently to present a generally smooth outer contourfor the work light when the hook is in the recess, while allowing manualaccess to the hook.

The openings may be in a non-planar surface of the casing such that theopenings are not blocked when the non-planar surface is placed adjacenta planar surface. The non-planar surface may be an arcuate surface.

The work light may have an overall width of approximately 60 millimetresor less, overall depth of approximately 43 millimetres or less, and anoverall height of approximately 301 millimetres or less, with thetransparent cover in the casing across a portion of the width of thework light.

The casing may include a handle portion and a head portion with the LEDsand LED mounting member and heatsink mounted in the head portion. Thehandle may have a cavity for receiving batteries to power the LEDs.

The work light may include a connection through which the work light canreceive energy for the LEDs. The connection may be for receiving abattery source of energy. The connection may be for receiving a furtherconnection to a source of energy external to the casing. The work lightmay include circuitry between the LEDs and the source of energy forcontrolling the flow of energy from the source of energy to the LEDs.

The casing may be configured to accept a battery source of energy and aconnection for receiving a source of energy external to the casing, suchthat the battery source of energy and the connection for receiving asource of energy external to the casing are interchangeable.

The work light may have a longitudinal axis with which the handle andhead are generally aligned. The transparent cover over the LEDs may bedirected out of line with the longitudinal axis. The transparent coverover the LEDs may be directed generally perpendicular to thelongitudinal axis.

The openings may open out of line with the longitudinal axis. Theopenings may open generally perpendicular to the longitudinal axis. Theopenings may be elongate slots extending generally parallel to thelongitudinal axis.

The at least one LED may be a plurality of LEDs and the LEDs may bemounted substantially on one plane to emit light substantiallyperpendicular to the plane. The LEDs may be mounted substantially alonga line in the plane.

The work light may include one optic for each LED of the at least oneLED, each optic associated with its respective LED such that radiationemitted by the LEDs and passing through the optics produces a beam thathas a beam angle of between approximately 40 degrees and 90 degrees.

The work light may emit a beam that has a central beam axis that isgenerally perpendicular to the longitudinal axis of the light.

The dissipation of heat from a heatsink in the work light may maintainthe temperature of the outside surface of the LEDs below approximately75 degrees Celsius in a range of ambient temperatures belowapproximately 35 degrees Celsius. The heatsink may be set back from anadjacent internal surface of the casing. The work light may include anair gap between the heatsink and the adjacent internal surface of thecasing.

The work light may include an accessory mount for receiving a work lightaccessory. The work light accessory may be a work light mounting device.The work light mounting device may be a stand for mounting the worklight on top of a generally horizontal surface. The work light mountingdevice may be a mounting bracket for mounting the work light to anexternal location.

In a sixth aspect the invention provides a work light including at leastone LED and an LED mounting member to which the at least one LED ismounted, a heatsink thermally connected to the at least one LED, acasing within which the at least one LED and heatsink are mounted. Inthis aspect the at least one LED emits light about a central beam axis,the casing has a head section, and the head section has a transparentcover through which light emitting from the LED assembly can escape thecasing. The heatsink has three dimensions: depth, width and height, theat least one LED is mounted adjacent and in thermal contact with theheatsink along the central beam axis in an opposite direction to whichthe at least one LED emits light, and the depth of the heatsink ismeasured along the central beam axis. The width and height of theheatsink are measured perpendicular to the depth and to one another, thehead section follows the general profile of the heatsink, and the depthof the heatsink is substantially less than the width of the heatsink andsubstantially less than the height of the heatsink, such that the worklight uses less space in the direction in which light is desired.

In any aspect the work light may include an elongate handle operativelyconnected to the head section. The handle may extend away from the headsection outside a volume bounded by the width and height of the headsection such that the handle does not increase the depth of the worklight in that volume.

The work light may include an elongate handle having a longitudinalaxis, wherein the handle is operatively connected to the head section,and wherein the longitudinal axis that extends through the head sectionin a direction generally perpendicular to the beam axis.

The handle may be generally cylindrical and extend from the head sectiongenerally perpendicular to the central beam axis. The handle may have adiameter that is less than the width of the head section. The depth ofthe head section may be less than the diameter of the handle.

In a seventh aspect the invention provides a work light including atleast one LED and an LED mounting member to which the at least one LEDis mounted, and the at least one LED emits light about a central beamaxis, a heatsink thermally connected to the at least one LED, and acasing within which the at least one LED and an LED mounting member andheatsink are mounted. In this aspect the casing includes a handlesection and a head section. The casing has two casing portions thatprior to assembly allow the insertion of the at least one LED and an LEDmounting member and heatsink into one of the casing portions, and afterassembly the casing portions together form the handle section and headsection, and the head section has a transparent cover through whichlight emitting from the at least one LED can escape the casing.

In an eighth aspect the invention provides a work light including a highpower LED that requires a heatsink for operation in a normal workingenvironment while preserving a useful life in prolonged use, a heatsinkfor use with the LED to preserve useful working life of the LED whenoperated in prolonged use, a casing of a substantially electricallynon-conductive material substantially enclosing the LED and heatsinksuch that components inside the casing are prevented from accidentalcontact with an operator, a transparent cover in the casing throughwhich a beam from the LED can escape the casing along a beam axis. Inthis aspect the heatsink and the LEDs together occupy a dimensiongenerally parallel to the beam axis, the casing has a head section and ahandle section, and the LEDs and heatsink are in the head section. Thehead section has an elongate profile that is smaller in a dimensiongenerally parallel to the beam axis of the light than in any dimensiongenerally perpendicular to the beam axis, the handle is elongate andextends away from the head section, and the handle extends away from thehead section outside a volume bounded by the dimensions of the headsection generally perpendicular to the beam axis such that the handledoes not increase the depth of the head section generally parallel tothe beam axis within that volume.

In any of the aspects the at least one light emitting diode maynominally have a lambertian radiation pattern. Where the work light hasa convex lens, the lens may have both a convex surface and a concavesurface. The diameter of the concave surface may be smaller than that ofthe convex surface. The concave surface may be curved more sharplytowards its edge than towards its center. The concave surface may beflat in its center.

In various other aspects a work light may include a handle, a light headsection, and one or more light emitting diodes. The handle and the lighthead may be comprised in a one piece structure that may be tubular. Thelight emitting diodes require heatsinking means and a heatsink isprovided in the light head. The heatsink may be a semicircular tube or achannel piece. The work light may produce a beam that is 40 to 90degrees wide. Most high power LEDs, produce beams that are more than 90degrees wide and optical devices are provided to concentrate the lightinto a narrower and more intense beam. The optical devices may be“optical pieces” that are made of plastic and use both refraction andreflection to concentrate the light into a beam. These optical piecesmay have a forward surface that is flat or curved or conical and thatlight exits the optic through. The forward surface of the optical piecemay or may not be textured with ridges, a random pattern, or other formof texturing. These optical pieces may have a rear reflective surfacethat may be flat, curved or conical. The rear reflective surface of theoptical pieces may or may not be textured with ridges, a random pattern,or other form of texturing. Any surface of the optical pieces may bedivided into regions that differ in shape and/or texturing or lackthereof. The optical pieces may be made of plastic and may be molded.The reflecting rear surface of the optic normally may reflect the lightby total internal reflection but alternatively may be coated with areflective material. The optical pieces may be used to produce beams 40to 90 degrees wide. Alternatively, two or more light emitting diodesthat produce excessively narrow beams may be aimed into differentdirections to achieve an adequately wide beam.

Alternatively, convex lenses may be used to produce the desired beamfrom the LEDs. Any convex lenses may be hemispheres or asphericplanoconvex lenses. Any convex lenses may be concavoconvex, symmetricbiconvex or asymmetric biconvex. Any curved surfaces on any lenses maybe spherical or aspheric.

The work light may have a ballast that accepts line voltage AC andprovides suitable DC with limited or regulated current for the lightemitting diodes. The ballast may be an electronic switching currentregulator. The ballast may be designed to work from a wide range of ACvoltages and may work both at 120 volts and at 240 volts. The ballastmay work with direct current over a wide range of voltages and may workwith DC of voltage as low as 12 or 12-14 volts. Alternatively, the worklight may work only from low voltage DC. The work light may containbatteries. The batteries may be rechargeable. The work light may containa battery charger. The work light may use inductive coupling from anexternal source of power in order to recharge any rechargeablebatteries. The work light may contain other parts such as a pagingreceiver to assist location of the work light, indicator lights such asa battery status indicator, and automated means to shut down the worklight should unfavorable conditions such as excessive temperature or lowbattery voltage occur.

The work light may contain batteries and also be able to be operatedfrom a detachable power cord. The work light may be able to haverechargeable batteries within it charged while it is operating whenreceiving power from a detachable power cord. The work light may be ableto be operated from more than one different power cord and associatedadapter. The different power cords and associated adapters may permitthe work light to receive power from power sources of differentvoltages, including 12 or 12-14 volts DC and line voltage AC.

The work light may contain rechargeable batteries that can be rechargedby placing the work light into a charging station. The charging stationmay also be able to charge a second battery set. The charging stationmay be able to simultaneously charge a work light having rechargeablebatteries and a second battery set. The charging station may have apaging transmitter.

The work light may be mountable on a tripod. Tripods may be madesuitable for mounting the LED work light onto. Such tripods may havemeans of providing power to the work light or charging rechargeablebatteries within the work light. A stand other than a tripod may be usedin lieu of such a tripod.

The work light may have a power cord and means to allow it to rotatewithout twisting the power cord. The work light may have a cord andmeans for accomplishing switching via a remote switch by pulling on it.The work light may have other remote switching means. The work light mayhave a cord that retracts into a reel.

In another further aspect the invention provides an LED work lightincluding a handle section and a head section, and a plurality of LEDsmounted in the head section, and means for the plurality of LEDs toreceive electrical power. Each LED within the plurality of LEDs isassociated with a lens that is located forward of its associated LED.The lens associated with each LED in the plurality of LEDs forms a beamby projecting an image of the forward region of its associated LED. Allof the said lenses associated with LEDs in the plurality of LEDs formbeams that merge together to form a useful combined beam substantiallybetween 40 and 90 degrees.

The lenses may have a focal length not greater than 1.4 times the widthof the forward regions of their associated LEDs. The lenses may havethickness at least half their diameters. Each lens may have thicknessgreater than the distance between each lens and its associated LED. Eachlens may have thickness at least twice the distance between each lensand its associated LED. Each lens may have a thickness equal to orgreater than half the diameter of each lens.

The lenses may be used to produce a beam having a higher percentage ofthe total light output being within the beam than would be the case ifthe lenses are omitted. The lenses may project a beam of light that isnot narrower than that produced by the LEDs.

The LEDs may be diffused LEDs. The diffused LEDs may have flat forwardsurfaces. The LEDs may include at least one white LED, at least one redLED, and at least one green LED.

In yet another aspect the invention provides an LED lamp including aplurality of LEDs to provide light that is useful for illuminationpurposes, wherein the plurality of LEDs that produces light useful forillumination further including one or more red LEDs, one or more greenLEDs, one or more white LEDs. The plurality of LEDs produce light thatis mixed to produce a combined light output that has color approximatingthat of a blackbody radiator and having a correlated color temperatureof 3,800 to 5,400 Kelvin.

The LED lamp may be an LED work light having a head section and a handlesection.

The photometric output from the one or more green LEDs may exceed thephotometric output of the one or more red LEDs. The ratio of thephotometric output from the one or more green LEDs to the photometricoutput from the one or more red LEDs may exceed 1.5. The photometricoutput from the one or more green LEDs may essentially approximate 1.8times that from the red LEDs. The photometric content from the one ormore green LEDs may be at least twice that of the red LEDs. Thephotometric content from the one or more green LEDs may be at least 3times that from the one or more red LEDs.

The red LEDs may contribute 3.5 to 18.5 percent of the total photometricoutput. The white LEDs may contribute at least half of the photometricoutput.

The LED lamp is a work light having a head section and a handle section.

In yet another further aspect the present invention provides an LED worklight including a handle section and a head section, and a plurality ofLEDs mounted in the head section, and means for the plurality of LEDs toreceive electrical power. Each LED within the plurality of LEDs isassociated with a lens that is located forward of its associated LED. Adiffuser is located forward forward of each LED and close to each LED,so that each LED produces an illuminated spot on the diffuser. The lensassociated with each LED in the plurality of LEDs forms a beam byprojecting an image of the illuminated spot on the diffuser. All of thesaid lenses associated with LEDs in the plurality of LEDs form beamsthat merge together to form a useful combined beam.

The LEDs may include at least one white LED, at least one red LED, andat least one green LED.

In a still further yet another aspect the invention provides an LED worklight including a handle section and a head section, and a plurality ofLEDs mounted in the head section, and means for the plurality of LEDs toreceive electrical power. Each LED within the plurality of LEDs isassociated with a lens that is located forward of its associated LED.Each LED has chips located substantially rearward of the forward surfaceof each LED. Each lens forms a beam of width 40 to 90 degrees wide. Thebeams merge together into a single beam that is 40 to 90 degrees wide.

The LED work light may further have a lens forward of each LED to formthe light from the LEDs into a beam that is 40 to 90 degrees wide. TheLEDs may have chips located substantially rearward of the edges of thefront surfaces of the LEDs.

Additional details that may form part of the above aspects, andadditional aspects of the invention including for example methods ofuse, will be evident from the detailed description hereof.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention and to show morewere clearly how it may be carried into effect, reference will now bemade, by way of example, to the accompanying drawings which show thepreferred embodiment of the present invention and in which:

FIG. 1 is a cross sectional side view of a work light in accordance witha first embodiment of the present invention,

FIG. 2 is a cross sectional top view of a work light in accordance witha second embodiment of the present invention,

FIG. 3 is a cross sectional side view of a work light in accordance witha third embodiment of the present invention,

FIG. 4 is an external view of a work light in accordance with a fourthembodiment of the present invention,

FIG. 5 is an external view of a work light in accordance with a fifthembodiment of the present invention,

FIG. 6 is a cross section view of an optical piece used in someembodiments of the present invention,

FIG. 7 is a set of external views of alternative optical-pieces that maybe used in various embodiments of the present invention,

FIG. 8 is a schematic circuit diagram of an electronic ballast used insome embodiments of the present invention,

FIG. 9 is a cross sectional side view of a work light in accordance witha sixth embodiment of the present invention,

FIG. 10 is a cross sectional side view of a work light in accordancewith a seventh embodiment of the present invention,

FIG. 11 is a cross sectional view of lenses used in some embodiments ofthe present invention,

FIG. 12 is a cross sectional top view of a work light in accordance withan eighth embodiment of the present invention,

FIG. 13 is a cross sectional side view of a work light in accordancewith the eighth embodiment of the present invention,

FIG. 14 is a cross sectional view of a lens assembly that may be used insome embodiments of the present invention,

FIG. 15 is a cross sectional side view of a work light in accordancewith a ninth embodiment of the present invention,

FIG. 16 is a frontal view of a work light in accordance with a tenthembodiment of the present invention,

FIG. 17 is a frontal view of a work light in accordance with an eleventhembodiment of the present invention,

FIG. 18 is a cross sectional side view of an alternate embodiment to theabove eighth embodiment of the present invention,

FIG. 19 is a cross sectional side view of a work light in accordancewith a twelfth embodiment of the present invention,

FIG. 20 is an external view of a work light in accordance with athirteenth embodiment of the present invention,

FIG. 21 is an exploded view of a work light in accordance with afourteenth embodiment of the present invention,

FIG. 22 is a frontal view of the work light of FIG. 21,

FIG. 23 is a side view of the work light of FIG. 21,

FIG. 24 is a rear view of the work light of FIG. 21,

FIG. 24 a is a top view of the work light of FIG. 21,

FIG. 25 is an exploded view of an alternative configuration of the worklight of FIG. 21,

FIG. 26 is a front perspective view of the work light of FIG. 21,

FIG. 27 is a rear perspective view of the work light of FIG. 21 with itshook in an upward position,

FIG. 28 is a rear perspective view of the work light of FIG. 21 with itshook in a retracted position,

FIG. 29 is forward perspective view of internal parts of a work light inaccordance with a fifteenth embodiment of the present invention,

FIG. 30 is a rear perspective view of internal parts of a work light inaccordance with the fifteenth embodiment of the present invention,

FIG. 31 is a rear perspective view of the fifteenth embodiment,including casing,

FIG. 32 is a cross-section of the work light of the fourteenthembodiment along the line A-A of FIG. 22,

FIG. 33 is an illustration of the work light of FIG. 21 in use on anaccessory stand,

FIG. 34 is an illustration of the work light of FIG. 21 in use with anaccessory mounting attachment,

FIG. 35 is an exploded perspective view of an end of the handle of thework light of FIG. 21 and a battery pack in accordance with anembodiment of the present invention for insertion into the handle,

FIG. 36 is a cross-section of an embodiment of a charging station inaccordance with an embodiment of the present invention in use with thework light of FIG. 21, and superimposed thereon, in use with the batterypack of FIG. 35,

FIG. 37 is an exploded perspective of the handle end of FIG. 35 and anexternal power adapter in accordance with an embodiment of the presentinvention, and

FIG. 38 is an alternate perspective view of the external power adapterof FIG. 37,

FIG. 39 is a cross sectional side view of a sixteenth embodiment of theinvention,

FIG. 40 is a cross sectional side view of a modification of thesixteenth embodiment,

FIG. 41 is a cross sectional side view of an example embodiment of alens for use in the work lights of FIGS. 39 and 40,

FIGS. 42 through 46 are ray tracing diagrams showing optical principlesof LED work lights employing the lens of FIG. 41, and

FIGS. 47 and 48 are ray tracing diagrams showing further opticalprinciples of LED work lights employing the lens of FIG. 41.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, a work light 100 has a handle 102 and alight head 103 that houses an LED heatsink 104. The LED heatsink 104 hasLEDs 101 mounted on it. The LED heatsink 104 as shown is in the shape ofa semicircular tube, which may or may not be constructed of a singlepiece of metal. The semicircular shape (best evident in FIG. 2) permitsthe heatsink 104 to be in contact with or very close to the structuralmaterial of the light head 102 so that heat can more easily escape intothe environment through the structural material of the light head 102.Alternatively, the heatsink 104 may be of a different shape or more thanone heatsink may be used.

The handle 102 and the light head 103 may be comprised in a single outercasing 105 a. Such a single outer casing 105 a may be tubular in shapeand made of transparent plastic such as acrylic or polycarbonate. Such atubular outer casing 105 a may have a semicircular tube shaped versionof the heatsink 104 contained in a manner such that the curved surfaceof such a semicircular tubular heatsink 104 is either fitted against orclose to the outer casing 105 a so that heat easily escapes from theheatsink 104 through the outer casing 105 a into the environment.Alternatively, a semicircular tubular heatsink 104 may merely beadjacent to or close to a substantial portion of an inner surface of thelight head 103. Should the heatsink 104 be fitted essentially within thelight head 103, it may have one or more extensions or protrusions thatprotrude into the handle 102. Extensions of the heatsink 104 wouldgenerally be desirable to assist in dissipation of heat produced by theLEDs 101, although other reasons may be found for extensions of theheatsink 104.

The use of a electrically insulative material, such as plastic, forcasing 105 a is advantageous when working in many environments, such asan automotive shop, where an externally conductive casing may provide anundesired conduction path for items with which it comes into contact. Anelectrically conductive casing 105 a could, for example, cause a shortcircuit between exposed terminals in an engine compartment.

The LEDs 101 are preferably of a high power type that typically requiresuse of a heatsink. The LEDs 101 may be supplied with heatsinks that maybe adequate or may require additional heatsinking means. LEDs 101 thatrequire heatsinking may have heatsink slugs or other surfaces that areintended to be attached to a heatsink. Alternative LEDs such as onesthat are heatsunk through any of their leads can be used, such as “highflux” or “spider” LEDs.

The LEDs 101 are shown as disposed in a linear fashion and aimed in thesame direction. In order to get a light output pattern that coverssufficient area to be useful, the LEDs 101 must have wider beams thanare provided by many existing LEDs such as typical Lumileds™ Luxeon™with optics LEDs. As an example, the LEDs 101 may be Lumileds Luxeontypes with an alternative optical piece 600 that forms a wider beam oflight from the LED 101 than is formed by the usual optical piecessupplied with the LEDs 101 by the manufacturer. A useful beam widthwould preferably be at least 40 degrees wide but no more than 90 degreeswide. Beam width is measured across the diameter of the beam in the caseof a circular or near circular beam.

Beam width of a work light is the width of that portion of light emittedfrom the work light that contains light that is adequate for use inworking for prolonged periods. It is possible that the work light mayproduce stray light outside the beam width; however, this light isgenerally wasted for the purpose for which the work light is intended.The beam width is typically expressed as an angle from the work lightsource of light.

Without limiting the generality of the above, an indication of beamwidth can be an angle from the work light source of light that defines abeam circumference where the light intensity is half the light intensityof the brightest part of the beam. LED manufacturers often use thisdefinition for determining the viewing angle of LEDs. Typically thebrightest part of an LED beam is at its center; however, some LEDs haveholes or dim spots at the center.

This provides a “floodlight” beam that is wider than the approximately10 degree wide beams of the usual Lumileds™ Luxeon™ with optics LEDs,wider than the beams of existing LED work lights of the Ferret™ brand,but more concentrated than the radiation patterns produced by LumiledsLuxeon LEDs that are not combined with added optical devices. A beamwidth of 40 to 90 degrees is wider than that of at least some models ofthe Ferret brand, but narrower than that of Lumileds Luxeon LEDs withoutadded optics. Lumileds LEDs without added optics tend to have aradiation pattern at least 110 degrees wide, and it has been founddesirable to concentrate the radiation into a beam that is narrower than110 degrees and more intense.

Thus, the optics described herein can be selected to change the beamwidth of the LED(s) within a range at least 40 degrees wide and not morethan 90 degrees wide, for example the optics may be selected to eitherwiden the beam width of an LED that has a beam width less than 40degrees or concentrate the beam width of an LED that has a beam widthgreater than 90 degrees. In addition, the optics described herein can beselected to change the light density across the beam width to create amore uniform light density. Furthermore, the optics can be selected tochange the beam edge sharpness of an LED, for example to provide asharper beam edge or a blurrier beam edge. Although the optics describedherein will not normally project a focussed image of an LED or any partthereof, it is possible to provide optics that will provide such afocussed image.

Alternative types of LEDs 101 may form a beam that is 40 to 90 degreeswide without additional optics. Such LEDs include Nichia's NCCW022.Although such LEDs may have a beam whose width is desirable, it may befound beneficial to add optics even if the beam width after use of suchoptics is 40 to 90 degrees. For example, optics may be added to achievea sharper edge of the beam since a beam with a sharper edge can providea sensation of greater illumination than a beam with a blurred edgedoes. On the other hand, a beam with a sharp edge may be considereddisadvantageous by having the sharp beam edge distract a user of thework light from seeing objects to be illuminated by the work light, inwhich case it may be desirable to blur the edge of the beam. The beamproduced by the LEDs may have a color nonuniformity that may becorrectable by additional optics. It may be found desirable to useadditional optics to change the width of the beam even if the beam widthboth with and without additional optics is in the range of 40 to 90degrees. It may be found desirable to change the light distributionwithin the beam even if the size of the beam is not changed, forexample, if the beam without additional optics has a central “hot spot”,a central “dim spot”, or an edge that is brighter than other parts ofthe beam. Optics, particularly those that produce a sharp edge, canresult in very limited light outside the desire beam width.

Although all of the LEDs 101 in the preferred embodiment of the worklight 100 are white LEDs 101, other LEDs can be used. For example, acombination of red, green and blue LEDs may be used so that theirindividual outputs combine to form white light or a usably whitishlight. It may be necessary to add diffusing means in order to mix theindividual LED outputs adequately to obtain white light. White lightobtained from mixing red, green and blue light may have an advantageover the light obtained from white LEDs since such a mixture of primarycolors can have enhanced color rendering. Furthermore, a combination ofcolored LEDs may have greater luminous efficacy than that of white LEDs.Combinations of colored LEDs other than red, green and blue may be foundto be usable to produce white light so as to be usable in alternativeembodiments of the present invention. For example, blue and green LEDsmay be combined with orange or amber or yellow LEDs in a way to producelight that appears white. Combinations of two colors such as red andcyan, orange and greenish blue, yellow and blue, or greenish yellow andeither violet or a violetish shade of blue can produce light thatappears white. However, such light that appears white but formed fromonly two colors normally has color rendering properties worse than thoseof white light obtained by other means. Colored LEDs of more than threedistinct colors may also be combined to produce white light. One or morewhite LEDs can be combined with one or more colored LEDs for purposessuch as achieving a different shade of essentially white light. Acombination of colored LEDs that can be used to produce essentiallywhite light may be combined with one or more white LEDs.

White LEDs traditionally have produced a slightly bluish white lighthaving a correlated color temperature typically near 6000 Kelvin.However, LEDs are becoming available in other shades of white, such as a“warm white” having a correlated color temperature typically near 3500Kelvin.

The work light 100 may use a “warm white” version of the LEDs 101 or acombination of LEDs 101 that produce different shades of an essentiallywhitish color, although it is presently preferred to have all of theLEDs 101 of the same color and of a correlated color temperature atleast 4000 Kelvin. Light of higher correlated color temperatures hasmore light of the blue and blue-green wavelengths that are favorable toscotopic vision, and this leads to a greater sensation of illuminationin dim and moderately dim areas.

A white LED is typically one having a blue-emitting LED chip with indiumgallium nitride active layer chemistry and a phosphor that converts someof the blue light to light that has a yellow overall color and aspectrum that extends from green through red. Some of the blue lightfrom the LED chip passes through the phosphor unutilized, and combineswith the yellow light from the phosphor to produce white light. Many ofsuch white LEDs produce light that is not uniform in color throughoutthe radiation pattern of such LEDs. Some other white LEDs have aradiation pattern that is reasonably uniform in color, but have the areathat the light is emitted from being nonuniform in color, and this canresult in a beam that is not uniform in color if optics are used to forma beam from such LEDs. Some Lumileds Luxeon white LEDs have phosphorapplied adequately evenly over their LED chips with no phosphor that ison surrounding surfaces, and this has solved color nonuniformityproblems. There are other white LEDs, such as ones having chips made ofzinc selenide, but these are presently not preferred since they havepoor color rendering properties and tend to produce beams that arenonuniform in color.

Although the preferred embodiment of the work light 100 produces whitelight, it may be found desirable to produce alternative embodiments thatproduce non-white light. For example, a variation of the work light 100that produces narrowband yellow or orange/yellow light or red light maybe found useful as a portable light source in an area being used as adarkroom.

It may be found desirable to operate the LEDs 101 with a magnitude ofcurrent other than that which the LEDs 101 are rated for. For example,use of a magnitude of current that is in excess of the ratings of theLEDs 101 may be desirable if cost savings are realized by using asmaller number of LEDs 101 and the life expectancy remains tolerable. Byfurther example, a lower current may be useful since indium galliumnitride LEDs often have increased efficiency when operated at lowercurrents. The efficiency of an InGaN LED can increase as current isdecreased until the current is as low as 10 percent or less of the LED'smaximum rated current. InGaN LEDs operated at currents anywhere from 10percent to 60 percent of their maximum rated continuous currenttypically achieve efficiency significantly greater than their efficiencyat their maximum rated continuous current. As an example of usage ofLEDs 101 at a magnitude of current much less than their maximumcontinuous current rating, Lumileds Luxeon III™ LEDs that haveperformance specified at 700 milliamps and a maximum rated current of 1ampere may be used with a current near 350 milliamps. Furthermore, if anLED work light 100 was originally constructed with or designed to useLEDs 101 that have a maximum rated current of 350 milliamps, then theoriginal LEDs 101 can be replaced with Lumileds Luxeon III LEDs toachieve an increase in efficiency.

A ballast 105 b is provided in the handle 102 to regulate the currentflowing through the LEDs. The ballast 105 b and any other ballastdescribed herein may also be referred to as an “LED driver circuit”. Theballast 105 b preferably a switching current regulator. Alternatively,the ballast 105 b may be an inductor or a capacitor combined with abridge rectifier, or a step-down transformer combined with a rectifierand current limiting means such as a resistor. The ballast 105 b may beprovided in a location other than in the handle 102.

The ballast 105 b receives power from a line cord 106. An outlet 107 maybe provided so that users of the work light 100 can plug tools or otherappliances into it.

Providing means such as those described above to operate the work light100 from line voltage AC is a desirable improvement upon existing LEDwork lights so that line voltage AC can be fed into the work light 100and an AC outlet can be contained in the work light 100. As with manyother features that can be used in other embodiments described herein,this feature can be used with other AC versions of the LED work lightsdescribed herein.

Variations of the work light 100 may be equipped with both a line cordand means to accept power from a battery since the ballast 105 b can bemade to work from low voltage DC as well as with line voltage AC. Theline cord 106 or the means to accept power from a battery or both may beremovable. Adapters may be provided for connecting the work light 100 tovarious sources of power. The line cord 106 may have a plug (not shown)that is suitable for receiving line voltage AC. Alternatively, the linecord 106 may have a different plug such as a plug that fits inautomotive cigarette lighter sockets so as to be suitable to receivepower from a DC source, such as a 12 or 12-14 volts DC source, or theplug may be clips that connect directly to an external DC source, suchas an automotive battery. Power supplies that produce low voltage DCfrom line voltage AC and that have an automotive cigarette lightersocket may be found convenient for powering any LED work light 100 thatoperates satisfactorily from 12 or 12-14 volts DC. Power suppliessuitable for supplying power to the work light 100 and having anautomotive cigarette lighter socket may have a circuit breaker or othermeans for protecting such a power supply from any application of anexcessive load, which an automotive cigarette lighter may be.

A hook 108 is preferably provided to hang the work light 100 fromautomobile hoods or other elevated objects. Additional hooks and/oradditional hanging means may be provided to permit hanging the worklight 10 in a variety of positions.

The work light 100 and other embodiments of the present invention mayinclude additional parts not shown such as switches for some or all ofthe LEDs and/or the outlet, dimming means for the LEDs, and one or moreindicator lights. Said indicator lights may indicate presence of lowvoltage DC within the ballast 105 b, reception of line voltage AC by thework light 100, or other functions or malfunctions.

Wiring 109 between the LEDs 101 and to the LEDs from the ballast 105 bis shown.

Referring to FIG. 3, an alternative embodiment of the present inventionis the work light 100 a that has an LED heatsink 104 a that has amounting surface shaped to aim the LEDs in different directions in orderto achieve a beam of desirable width, such as 40 to 90 degrees. The LEDs101 a have narrower beams than do the LEDs 101 shown in FIG. 1. In lieuof a single heatsink 104 a that has a mounting surface that causes theLEDs 101 a to be aimed into different directions, the LEDs may haveindividual heatsinks so that a single heatsink 104 a with a speciallyshaped mounting surface is not required.

The LEDs 101 a may be of a type with optics added, such as LumiledsLuxeon with Optics, which typically have beams 10 to 20 degrees wide.The LEDs 101 a may be of a type without additional optics such as NichiaNCCW023, which have beams 35 degrees wide. Optics may be added to adjustcharacteristics of the beam produced by the work light 100 a even if thewidth of the beam produced by the work light 100 a is 40 to 90 degreeswithout additional optics.

Like the LEDs 101 described above, the LEDs 101 a are preferably whiteLEDs.

The outer casing 105 a is shown, comprising a light head section 103 aand a handle section 102 a. For ease of description other parts shown inFIG. 1 including ones necessary for this alternative work light 100 a tooperate are not shown.

Other alternative embodiments may have alternative means of divertingthe beams from each of the LEDs 101 a into slightly different directionseven if the LEDs are mounted on a flat heatsink, such as prisms placedforward of some or all of the LEDs 101 a.

A beam that is oblong may be found desirable. Having the LEDs 101 aaimed into different directions can achieve an oblong beam. For example,some of the LEDs 101 a may be tilted vertically while none of the LEDs101 a are tilted horizontally in order to achieve a beam whose verticalwidth is greater than its horizontal width. A desirable oblong beam canhave both vertical and horizontal width in the range of 40 to 90degrees. Other means of achieving an oblong beam are possible in otherembodiments of the present invention, such as use of LEDs that produceoblong beams or use of optics that form oblong beams from LEDs thatotherwise do not produce oblong beams.

Referring to FIG. 4, a further alternative work light 100 b has adistinct light head 403 and handle 402 connected to each other by aflexible tube 401. When the flexible tube 401 is straight, it has anaxis shared with that of the light head 403. The light head 403 containsLEDs 101 and associated optical pieces 600 and a heatsink 403 arrangedsuch that light is produced from one side of the light head 403.

Although the tube 401 is flexible it may be rigidly flexible such that auser can manipulate the light head 403 with respect to the handle 402 inorder to position the light head in a given direction and release thelight head so that it maintains that position during use. An articulatedtube 401 may be useful for this purpose.

Wires 409 necessary for operating the LEDs 101 pass through the flexibletube 401. preferably an electronic ballast 105 b is provided to operatethe LEDs 101 from AC line voltage. The electronic ballast 105 b is shownas being in the handle 402 but it may be provided in the LED head 403 orelsewhere.

A hook 408 is provided on the light head 403 to hang the work light 100b from suitable elevated objects. Additional hanging means may beprovided on the work light 100 b.

Even further alternative embodiments may have a distinct light head 403and handle 402 connected by a non-flexible tube or a combination of oneor more flexible tubes 401 and one or more non-flexible tubes.

Electrical components or devices necessary for operation of the LEDs maybe provided outside the work light 100 b.

Referring to FIG. 5, an additional further alternative embodiment of thepresent invention is a work light 100 c that has a flexible tube 401, ahandle 402 and a light head 503 that is different from those shown inFIGS. 1, 3 and 4 that where the LEDs 101 and their associated opticalpieces are mounted generally perpendicular to the axis of the lighthead. The light head 503 has LEDs 101 and their associated opticalpieces 600 mounted with their axes generally parallel to the axis of thelight head 503.

The light head 503 has a metal body piece 503 a that serves as aheatsink for the LEDs 101. A transparent cover/lens assembly 503 b isprovided to protect the LEDs 101 from impacts.

A hook 508 is provided at the base of the handle so that the work light100 c can be hung with the light head 503 pointing downwards. Anadditional hook (not shown) may be added to the light head 403. This maybe especially useful as the light head 403 produces light in a directionperpendicular to its axis and downwardly projecting light is useful inmany circumstances when a work light is hanging, such as for examplefrom under an automotive hood. Other hooks or hanging means may also beprovided. A line cord 106 is connected to the handle 402, although ifdesired the line cord could be connected to the light head to createalternative embodiments based on the principles described herein.

Again, necessary electrical connections and components necessary foroperating the LEDs 101 are not shown in the work light 100 c.

The handle 402 may be replaced by an alternative structural member suchas a base that the hook 508 is attached to. The ballast, such as ballast105 b from other FIGS. may be contained anywhere within the work light100 c.

In work lights 100, 100 a, 100 b, 100 c, four LEDs 101 are shown. Adifferent number of LEDs may be used.

Referring to FIG. 6, in the preferred embodiment of the presentinvention light from each of the LEDs 101 is partially collimated into abeam preferably between 40 and 90 degrees wide by an optical piece 600.This optical piece 600 uses both total internal reflection andrefraction to achieve this beam characteristic.

Similar optical pieces have been in use for years, but they are usuallymade to collimate the light into a narrower beam generally 20 degreeswide or narrower.

The optical piece 600 is preferably molded from a transparent plasticsuch as acrylic. Alternatively, it may be machined. Furtheralternatively, it may be made of a material other than moldable plasticor a material other than plastic such as glass. Preferably, the opticalpiece 600 is essentially paraboloidal in shape. The optical piece 600preferably has a hollow internal region 601 that is cylindrical inshape. A dome 602 at the end of the hollow cylindrical region 601collects and partially collimates some of the light 610 from the LED101. Alternative embodiments of the present invention may have thissurface of a shape different from that of the dome 602. A curved surfacehere may be substituted with a combination of different surface shapesincluding but not limited to truncated conical surfaces and/or flatfacets that may approximate a curved surface.

Most of the light 610 from the LED 101 is collected by the surface ofthe hollow cylindrical region 601's side surface 605, and the directionof this light changes to a direction less parallel to the axis of theoptical piece 600 as a result of refraction. Afterwards, this refractedlight 611 is reflected into a largely forward direction by the rearsurface 603 of the optical piece 600. The rear surface 603 will normallyreflect the light via total internal reflection and normally does notrequire a reflective coating, but in alternative embodiments areflective coating may be added to the rear surface 603. Such areflective coating may be metal such as aluminum, silver or thereflective coating may be a nonmetallic coating such as multiple layersof nonmetallic “dielectric” material. Further alternatively, a reflectorcan be added behind the optical piece 600 if total internalreflection-fails to reflect some light.

Most of the reflected light 612 is reflected into directions such thatthe light converges towards the axis of the optical piece 600. Thislight then exits the optical piece 600 through the forward surface 604,where refraction increases the converging tendency of this light. Theforward surface 604 is shown as a flat surface, but the forward surfacemay be convex, concave, or of a different shape. The exiting light 613diverges from the optical axis of the optical piece 600 after passingthrough a region forward of the optical piece 600 where the exitinglight 613 is most converged.

In lieu of the optical piece 600 other optical means to concentrate thelight from an LED 101 can be used, such as a concave mirror or a convexlens. Such a convex lens may be biconvex or planoconvex or it can have adifferent convex shape. Such a lens may be a Fresnel lens.

The optical pieces typically used with Lumileds Luxeon LEDs aretypically approx. 18 to 20 millimeters in diameter. The optical piece600 may be of this size or it may be of a different size. A smaller sizeof the optical piece 600 can be achieved since the optical piece 600does not have to produce as tightly collimated a beam as is achievedfrom the usual optical pieces for Lumileds Luxeon LEDs.

Referring to FIG. 7, there are numerous possible variations in thedesign of the optical piece 600.

The preferred embodiment of the optical piece 600 has a nearlyparaboloidal rear surface of such shape that light is reflected forwardsbut not collimated into as narrow a beam as possible. The light is overconvergent, such that it converges into a small region that is a smalldistance forward of the optical piece 600 and diverges at the desiredrate after passing through this area of maximum convergence.

A first alternative optical piece 600 a has a curved rear surface 603 adesigned to form a diverging beam as opposed to a beam that initiallyconverges and then diverges past a point where it is most converged. Thenecessary difference in shape between the preferred optical piece 600and the first alternative optical piece 600 a is that the rear surface603 a of the first alternative optical piece 603 a tapers more quicklythan does the rear surface 603 of the preferred optical piece 600.

A second alternative optical piece 600 b has a convex forward surface604 b and a conical rear surface 603 b. Other alternative embodiments ofthis optic may have a conical rear surface combined with a curvedforward surface to achieve the desired radiation pattern. The forwardsurface may be convex or concave. The forward surface may be convex insome areas and not convex in other areas. The forward surface may beconcave in some areas and not concave in other areas. Furtheralternatives of this optic can be made with both the forward surface andthe rear surface curved. Curved surfaces may have a spherical shape oranother shape such as paraboloidal or hyperboloidal.

A third alternative optical piece 600 c has part of its rear surface603-1 c in a nearly paraboloidal shape and part of its rear surface603-2 c conical in shape. Other alternative embodiments of this opticalpiece 600 c can have a rear surface of a different shape. Such otheralternative embodiments of this optical piece 600 c can have a rearsurface divided into regions that have different shapes, such as oneregion being conical and another region having a spherical curvature.The forward surface in optical piece 600 c is flat, but alternatively itmay be convex or concave. Further alternatively, part but not all of theforward surface may be convex and part but not all of the forwardsurface may be concave.

Curved regions of the forward surface may have a spherical ornonspherical curvature shape.

A fourth alternative optical piece 600 d has a shape designed to producea beam that is more collimated than desired, but its forward surface 604d is textured to diffuse the beam so as to make it diverge at thedesired rate. The forward surface 604 d may have a random texture.Alternatively, the forward surface 604 d may have a distinct pattern ofsaid texture, such as radial ridges (as shown) or concentric ridges.Such ridges may have various shapes such as triangular or cylindrical.

A fifth alternative optical piece 600 e has a forward surface 604 edivided into regions that have different texture patterns. These regionsmay be concentric as shown or they may be arranged differently. Thedifferent forward surface texture patterns may comprise one concentricregion with radial ridges and another with concentric ridges as shown,but different texture patterns including but not limited to one or morerandom texture patterns may be used. Alternatively, some of the forwardsurface may not be textured. Further alternatively, part or all of theforward surface may be curved and part or all of the forward surface maybe textured.

A sixth alternative optical piece 600 f has texturing of the rearsurface 603 f to make the beam less collimated. Alternatively, only partof the rear surface is textured. Further alternatively, texturing can beused on part or all of the rear surface 603 f in combination withtexturing of part or all of the forward surface. Various combinations ofsurface curvature and texturing may be found to produce a desirablebeam. The texturing may be concentric ridges as shown or in another formsuch as radial ridges, a different non-random pattern, or a randomtexture pattern on the rear surface 603 f.

A seventh alternative optical piece 600 g has a shape that does not haverotational symmetry about an optical axis. This alternative opticalpiece 600 g as shown has a pyramid shape. The surfaces shown are shownas flat but alternatively part or all of any surface may be curved ortextured or both curved and textured. Other shapes are possible, such asa cone that is elongated in a direction perpendicular to its opticalaxis so that it has an elliptical shape.

An eighth alternative optical piece 600 h has a flat region 602 h inlieu of the dome 602 of the preferred optical piece 600.

A ninth alternative optical piece 600 i has the hollow tubular region601 i tapered. The taper may be straight (as shown), curved, or havingboth straight and curved portions, or more than one portion that tapersstraightly at different rates. Part of the hollow tubular region 601 imay be not tapered. The hollow tubular region 601 i may or may not (asshown) be tapered to a point that precludes an end surface 602 i of thehollow tubular region 601 i.

A tenth alternative optical piece 600 j can have part or all of its rearsurface 603 j in the form of a series of truncated cones that havedifferent included angles so as to simulate a curved surface. Othersurfaces of the optical piece may have a compound curve substituted witha series of truncated conical surfaces.

An eleventh optical piece 600 k may have part or all of any of itssurfaces effectively curved by an arrangement of facets. Any facetedsurface may be divided into concentric circular areas (as shown) orother areas that have different facets. As shown, facets are used tosimulate curvature of the rear surface 603 k.

Alternative embodiments of the optical piece 600 may incorporate anycombination of the above variations and/or similar variations.

With any of the various optical pieces 600-600 k the space between theLED 101 and the optical piece 600-600 k is preferably filled with air.Preferably this space has a refractive index less than that of thematerial that the optical piece 600-600 k is made of.

A twelfth alternative optical piece 600 l is in the form of a cylinderwith a dome tip. A depression 605 l in the base of this optical piece600 l accommodates the LED 101. The combination of this optical piece600 l and the LED 101 simulates a large LED that is of a traditional“bullet style” and that has beam characteristics obtainable from any ofthe traditional “bullet style”, especially from any of the “5 mm” or“T1-3/4” LEDs. Preferably the space between the LED 101 and this piece600 l is filled with glue or plastic or other transparent material 606l. The transparent material 606 l can be liquid but is solid incurrently preferred embodiments using this embodiment of the opticalpiece 600 l.

Alternatively the space between the LED 101 and the optical piece 600 lcan be filled with a gas other than air, a gas at a pressure other thanatmospheric pressure, or a vacuum.

A reflector 607 l may be provided surrounding the optical piece 600 l todirect forward light that escapes from the sides of the optical piece600 l. An additional optical component 608 l may be placed forward ofthe optical piece 600 l to alter the characteristics of the beam orradiation pattern formed by the optical piece 600 l. This additionaloptical component 608 l may be a lens, a diffuser, a prismatic componentor a lens that has diffusing characteristics. Such an additional opticalcomponent may affect only part of the light that passes through theoptic piece 600 l.

The optic piece 600 l may be placed forward from the LED 101 such thatit affects only some of the light produced by the LED 101. In such acase, light that is not affected by the optic piece 600 l can beconcentrated by a reflector 607 l or by other optical components. In apossible alternative embodiment of the present invention, some of thelight escaping the optic piece 600 l does not need to be redirected byother optical components while some light escaping the optic piece 600 lis affected by an additional optical component 608 l.

The additional optical component 608 l is shown placed forward of theoptic piece 600 l, but it may be attached to the optic piece 600 linstead. More than one additional optical piece 608 l may be used inalternative embodiments of the present invention. Space forward of theoptic piece 600 l may be filled with a material other than air inalternative embodiments of the present invention.

Alternative embodiments may include one or more optical pieces 600 ofone shape and one or more optical pieces 600 of a different shape in onework light. Similarly, one or more LEDs may each be combined with anoptical piece 600 and one or more LEDs may each be combined with adifferent optical means of concentrating their light such as a convexlens.

The beam produced by one or some of the LEDs 101 may be brighter in thecenter than towards the edges of the beam, while one or more of theremaining LEDs 101 produces light into a beam that is brighter towardsits edges than towards its center. Such beams that have differentpatterns of non-uniform light intensity can be combined to produce amore uniform beam. Various forms of non-uniform beams or noncircularbeams may be combined into a desired beam. For most uses it is desiredto have the beam resulting from the combination of each of the beamsformed from their respective LEDs both uniform and circular. However, itis possible that alternative embodiments with a different beam shapeand/or a non-uniform beam may be desired.

Referring to FIG. 8, the LEDs 101 are provided regulated current from anelectronic ballast circuit 800 comprised in the ballast 105 b.

In the circuit 800, AC power is accepted by a line cord plug 803 and theline cord 106. The AC is rectified by a bridge rectifier 804. A fuse 801is preferably provided to prevent catastrophic failure. The output ofthe bridge rectifier 804 feeds a filter capacitor 805 that partiallyfilters the DC.

A line current resistor 802 is preferably provided to limit the peakcurrent drawn through the bridge rectifier by the filter capacitor 805when the instantaneous line voltage exceeds the voltage across thefilter capacitor 805. The filter capacitor 805 is preferably anelectrolytic type. An additional capacitor 806 of a smaller capacitanceand of a type that is more conductive at high frequencies may beprovided in parallel with the filter capacitor 805.

A dropping resistor 821 and a zener diode 822 provide low voltage DCfrom the higher voltage DC provided by the bridge rectifier 804 andfilter capacitor 805. This lower voltage DC is the power supply for thetimer integrated circuit 814.

Preferably, the timer integrated circuit 814 is a low power or “CMOS”version of the “555 timer”. The timer 814 may be one of the two sectionsof a “556 dual timer” integrated circuit or may otherwise beaccomplished by alternative circuitry that can be found to emulate a“555 timer” integrated circuit for the purposes served by the timerintegrated circuit 814.

The control voltage for the timer integrated circuit 814 is provided bya dropping resistor 820 and a combination of voltage reference diodes818 a and 818 b. Preferably, diode 818A is a red light emitting diodeand diode 818 b is a silicon switching diode. Other diodes can be used.A single diode may be found suitable in lieu of the combination ofdiodes 818 a and 818 b. The control voltage may be obtained by usingother means such as a voltage reference integrated circuit in lieu ofthe diodes 818 a and 818 b and the associated dropping resistor 820. Acapacitor 819 is provided in parallel with the voltage reference diodes818 a and 818 b in case it is necessary to absorb interference, such asfrom nearby spark plug wires.

When power is first applied, the current flowing through the inductor809, transistor 807 and current sensing resistor 808 is zero. Because ofthis, the voltage across the current sensing resistor 808 is less thanthe control voltage. In addition, the voltage across the timingcapacitor 816 is zero. Under this set of conditions, the output of theintegrated circuit timer 814 is “high” and causes the transistor 807 toconduct. This allows current to flow through the LEDs 101, the inductor809 and the current sensing resistor 808. This current increasesgradually and the voltage across the current sensing resistor 808accordingly increases gradually.

The “threshold” pin of the integrated circuit timer 814, marked “TH” inFIG. 8, is connected to one end of the current sensing resistor 808 soas to sense the voltage across the current sensing resistor 808. Whenthe voltage across the current sensing resistor 808 exceeds the voltageacross the voltage reference diodes 818 a and 818 b, the output of theintegrated circuit timer 814 becomes “low” and causes the transistor 807to become nonconductive. When the transistor 807 is nonconductive,current that is flowing through the inductor 809 and the LEDs 101 willflow through a diode 811. When this current is flowing through the diode811 instead of through the transistor 807, this current is graduallydecreasing.

The combination of the resistor 812 and the diodes 813 a, 813 b and 813c is provided to prevent interference to the integrated circuit timer814 from the transistor 807 that can result from the transistor 807switching the inductor 809. The diodes 824 and 825 are provided to shuntto the supply rails any interference or undesirable voltage spikes thatwould otherwise damage the transistor 807 or cause malfunction of theintegrated circuit timer 814.

When the output of the integrated circuit timer 814 is “high”, itcharges the timing capacitor 816 through a charging resistor 815 and ablocking diode 827. When the output of the integrated circuit timer 814is low, the timing capacitor 816 is gradually discharged through atiming resistor 817 by the “discharge” pin of the integrated circuittimer. The blocking diode 827 prevents the timing capacitor from beingdischarged quickly through the charging resistor 815.

When the voltage across the timing capacitor 816 decreases to less thanhalf the voltage across the reference diodes 818 a and 818 b, the outputof the integrated circuit timer switches from “low” to “high”. At thistime the current flowing through the inductor 809 and the LEDs 101 hasusually not decreased to zero. However, values for the timing resistor817, timing capacitor 816 and inductor 809 can be selected so that thiscurrent does decrease to zero. When the output of the integrated circuittimer 814 switches from “low” to “high”, current flowing through theinductor 809 and the LEDs will flow through the transistor 807 again andwill increase again whether or not it has decreased to zero by the timethe transistor 807 is made conductive.

In the preferred embodiment of the present invention, the transistor 807is a MOSFET. Other types of transistors will work, including insulatedgate bipolar transistors and conventional bipolar transistors.Conventional bipolar transistors will typically require a resistor (notshown) to be added in series with their base terminals when they arecontrolled by integrated circuit timers of the common “555” types.

The current flowing through the LEDs 101 and the inductor 809 willalternately increase and decrease in a roughly linear fashion. Themaximum magnitude of this current is independent of the supply voltageas long as the supply voltage is high enough to cause this current to belarge enough to cause the voltage across the current sensing resistor808 to exceed the voltage across the voltage reference diodes 818 a and818 b. Because of this, it will have a characteristic average magnitudeand is therefore effectively regulated.

Preferably, a capacitor 810 is added in parallel with the LEDs 101 tosmooth the waveform of the current that flows through the LEDs 101. Thishas been found to improve the efficiency of the LEDs currently beingused as described herein. Other LEDs may not benefit from such smoothingof the current waveform, in which case it may be preferable not to usecapacitor 810. Alternatively, capacitor 810 may be of a value that istoo small to smooth the waveform of the current that flows through theLEDs 101. Such a capacitor 810 may be useful for absorbing interferencecaused by switching of the transistor 807 and/or the related suddenchanges in the voltage across the inductor 809. Such interference mayotherwise interfere with proper operation of the ballast circuit 800.

If appropriate components are selected, the electronic ballast circuit800 can work over a wide range of AC voltages including 110 and 240volts and all voltages in between. An advantage of an electronic ballastthat works both at 120 volts and at 230 volts is that the same circuitcan be used in different countries that have different available ACvoltages. A work light 100 that is designed to be usable in differentcountries may have a variety of detachable line cord plugs 103 provided.

The inductor 809 would normally be a type having a gapped ferrite core.Other types may be suitable. For example, such other types may have acore made of a ferrite that has low permeability and does not requiregapping. Alternatively, such other inductor types may have aferromagnetic core made of a material other than ferrite, such aspowdered iron or laminated transformer steel. It is possible to make theinductor 809 with no magnetic core at all, although this requires thatthe inductor 809 to be larger and heavier than it would be with a gappedferrite core.

The electronic ballast circuit 800 will also work with a DC power sourceas well as with an AC power source. Such a DC ballast may bealternatively referred to as an LED driver circuit. By using a smallnumber of LEDs 101 and with an appropriate selection of components suchas a low enough value for the dropping resistor 821, this electronicballast circuit 800 can work at a selected DC input voltage, such as 12or 12-14 volts. Alternative arrangements such as a parallel combinationof more than one “string” of a small number of LEDs 101 and a currentdividing resistor can be used to achieve a sufficiently low minimumvoltage requirement of the electronic ballast circuit 800.

LED lights can benefit from ability to be operated over a wide range ofvoltages, such as both 120 and 240 volts AC, or both line voltage AC andlow voltage DC, even if they produce beams other than 40 to 90 degreeswide and/or have LEDs other than LEDs 101 that have or requireheatsinking means and/or are LED lights other than work lights havinghandles.

LED work lights that have the electronic ballast circuit 800 includingthe bridge rectifier 804 and that can be operated from low voltage DCcan benefit from working properly regardless of the polarity of the lowvoltage DC being used.

Any or all benefits of the electronic ballast circuit 800 can beachieved by alternative means. Such alternative means may be a switchingcurrent regulating circuit that is different from the electronic ballastcircuit 800. Such alternative means may be a switching currentregulation circuit that has a microprocessor. Such alternative means mayinclude a linear regulator if the power losses of a linear regulator areacceptable.

Referring to FIG. 9, an LED work light 900 can be made like the LED worklight 100 of FIG. 1, except it has convex lenses 1100 like thosedescribed below and shown in FIG. 11 in lieu of refractive-reflectiveoptics 600 forward of the LEDs 101.

The work light 900 has a casing 105 b that is transparent about the headsection. Any portion of the outer casing 105 b that does not cover(block desired light from) the lenses 1100 need not be transparent.

The convex lenses 1100 may be the aspheric concavo-convex lens of FIG.11. Alternatively, the convex lenses 1100 may be of a different shapesuch as hemispheric or an aspheric planoconvex shape. Any asphericsurface may be an ellipsoid or a different aspheric shape such as aparaboloid, hyperboloid, a rotated fraction of a cycle of a sinusoid orany mathematical combination of any of these and/or a spherical curve.

Like the work light 100 of FIG. 1, the work light 900 comprises a handle102, a heatsink 104, a ballast 105 b, a power cord 106, an outlet 107,and a hook 108. Other arrangements are possible. Any embodiments thatare powered by low voltage DC may contain one or more batteries (such asbatteries 1208 of FIG. 13) that may or may not be rechargeable.Embodiments powered by low voltage DC may be powered by an externalpower source. Embodiments powered by low voltage DC will not usuallyhave the outlet 107. Embodiments that are powered by line voltage AC mayor may not have the outlet 107.

Referring to FIG. 10, an LED work light 1000 can be made like the LEDwork light 900 of FIG. 9, except the convex lenses 1100 are an integralpart of a transparent light head outer casing 103. The transparent outercasing may be but is not necessarily molded. If the transparent casing103 is molded, it may be machined and/or polished afterwards. As anexample, sink marks may form on the lenses 1100 during or after theirsolidification, and such sink marks may need to be machined and polishedor otherwise repaired.

Referring to FIG. 11, a concavo-convex lens 1100 and a hemisphericplanoconvex lens 1100 a are shown. The concavo-convex lens 1100 or thehemispheric planoconvex lens 1100 a can be used to concentrate the lightfrom a wide angle LED into a suitable beam, such as a beam at least 40but no more than 90 degrees wide.

The lens 1100 has a forward surface 1101, a rear surface 1102 and anaxis 1103.

A hemispheric variation 1100 a of a convex lens is also shown. A usablebeam has been achieved by placing a hemispheric the lens 1100 a at avery short distance forward of a Lumileds Luxeon LED that has alambertian radiation pattern. A lambertian radiation pattern is onewhere the light intensity at any given angle from the axis of the lightsource is the intensity on the axis multiplied by the cosine of theangle from the axis. The light intensity decreases as the angle from theaxis increases, and at an angle of 60 degrees from the axis is half theintensity on the axis of the LED. A hemispheric lens 1100 a has atendency to compensate for this by concentrating light more greatly atthe edge of the beam formed by it than at the center of this beam. Theresult is a beam that is reasonably even in intensity, although a bright“ring” sometimes forms at the edge of the beam.

A hemispheric lens 1100 a may be found to work adequately with otherLEDs. One such other LED is the Lumileds Luxeon LEDs having the“batwing” radiation pattern. In this radiation pattern, the LED producesa beam that is approximately 110 degrees wide and with its edge brighterthan its center so that the LED evenly illuminates within its beam aplanar surface that is perpendicular to the axis of the LED. This effectmay be unfavorably compounded by the tendency of a hemispheric lens 1100a to concentrate light more at the edge of the beam formed from such alens 1100 a than at the center of the beam, and the result may be a beamthat is much brighter towards its edge than in its center. However, ahemispheric lens 1100 a that is smaller in diameter may result in a beamwhose edge is blurred sufficiently to remedy the excessively brightnessof the edge of the beam that would otherwise result.

The radiation pattern that Lumileds refers to as “batwing” isapproximately “inverse cosine cube”. Throughout most of the beam, theintensity at any given angle off axis is approximately equal to theintensity on axis divided by the cube of the cosine of the angle fromthe axis. Such a radiation pattern produces an even illumination patternon a planar surface that is perpendicular to the axis of the beam.Lumileds named such a pattern “batwing” because of the shape of a graphof intensity as a function of angle from the axis of the radiationpattern.

Usable versions of the hemispheric lens 1100 a include plastic cabachonsthat are available from plastic shops, which may be made by casting aresin of an acrylic such as methyl methacrylate or a combination ofstyrene and an acrylic such as methyl methacrylate.

The hemispheric lens 1100 a has a front surface 1101 a, a rear surface1102 a, and an axis 1103 a.

The lens 1100/1100 a may be made of a thermoplastic such aspolymethylmethacrylate or another acrylic or a thermoplasticpolycarbonate. The lens 1100/1100 a may be made of a non-thermoplasticmaterial such as a polycarbonate resin, an acrylic resin, a resin havingstyrene, a resin that is a combination of styrene and an acrylic such asmethyl methacrylate, or epoxy. The lens 1100/1100 a may be made of anon-polymer material such as glass.

Variations of the lens 1100 that are not concavo-convex are not limitedto the hemispheric variation 1100 a. Variations of the lens 1100 may beplanoconvex but not hemispheric, such as being aspheric or comprising afraction of a sphere other than a hemisphere. Aspheric planoconvexvariations of the lens 1100 may be ellipsoidal, paraboloidal or of adifferent aspheric shape.

The lens 1100 would typically be molded, such as by injection molding orcasting. Alternative means of producing a lens 1100 exist, such asmachining. A lens 1100 that is molded may have to be machined afterwardsfor purposes such as repairing sink marks. The lens 1100 may be made insuch a way that it requires polishing. The same is true for variationsof the lens 1100 that are not concavo-convex, such as the hemisphericlens 1100 a.

Any lens 1100 or 1100 a may be touching or not touching the LEDproducing the light formed into a beam by the lens 1100 or 1100 a.

A lens 1100 or 1100 a with an overall diameter ½ inch (12.7 mm) orlarger has been found to work well with LEDs having a lambertianradiation pattern. A hemispheric lens 1100 a with an overall diameter of⅝ inch or larger produces an impressively uniform beam having anattractively sharp but slightly excessively bright edge if used with aLumileds Luxeon LED with a lambertian radiation pattern and a nominalpower rating of 1 or 3 watts. A hemispheric lens 1100 a with an overalldiameter at least ⅝ inch has been found to work well with Cree'sXL7090-WHT LED. This LED nominally has a lambertian radiation pattern,but actually radiates less light far off axis than an LED with a truelambertian radiation pattern produces. A hemispheric lens 1100 a with anoverall diameter of ½ inch (12.7 mm) has produced a usable beam fromLumileds Luxeon LEDs having the “batwing” radiation pattern and anominal power rating of 1 watt. If a hemispheric lens larger than ½ inchin diameter is used with a “1 watt” Luxeon LED with the “batwing”radiation pattern, the resulting beam tends to be brighter at its edgethan in its center. Other LEDs may work best with a different size oflenses 1100 or hemispheric lenses 1100 a. Lenses 1100 or hemisphericlenses 1100 a of larger sizes can usually be used with little or no illeffect on performance, especially with LEDs having a lambertianradiation pattern. Having a lens 1100 or hemispheric lens 1100 a of sizelarger than necessary for good results may be useful to produce worklights that can use different LEDs, such as larger or multichip LEDsthat may require larger lenses. Lenses 1100 or hemispheric lenses 1100 aof size larger than necessary for good results may be found beneficialby having an attractive appearance.

A hemispheric lens 1100 a typically produces a beam that is slightlybrighter at its edges than at its center. This occurs at least in partfrom rays hitting a wide range of the outer region of the rear surface1102 a being refracted into a narrow range of angles from the axis 1103a of the hemispheric lens 1100 a, with this narrow range of anglesapproximating the critical angle of the lens material if the rearsurface 1102 a is flat. Changing the flat rear surface 1102 a into aconcave one like the concave rear surface 1102 of the concavo-convexlens 1100 can prevent this from happening.

A concave rear surface 1102 would preferably approach being flat in itscentral region, while being curved towards its edges. Such a concavesurface 1102 may be of a shape mathematically defined by depth as afunction of radius from the axis 1103 being a constant minus radiusraised to a power greater than two. If the rear surface 1102 is concave,it may alternatively be of a different shape or it may even bespherical. If the rear surface 1102 is concave, it may have a flatcentral portion with a curved outer region. If the rear surface 1102 isconcave with curvature only in its outer region, the curve may or maynot be a section of the surface of a toroid. If the rear surface 1102 isconcave, the shape may be achieved by machining with an end mill, drillbit or router bit whose tip has been machined into the desired shape.Other means are possible for achieving a concave form of the rearsurface 1102 if the lens is made with a flat or otherwise differentsurface in an earlier production step. Such machining after an earlierproduction step may be useful for removing any sink marks that may occurin molded versions of the lens 1100.

If the rear or concave surface 1102 is flatter towards its center thantowards its edge, the central region of this surface 1102 may either becompletely flat or may have some curvature. The lens 1100 may be madewith the rear surface 1102 generally concave but with part of thissurface 1102 such as the central region convex or even conical.

A concavoconvex lens 1100 can assist in more evenly spreading light overthe area of the beam. Without the concave portion emitted light tends tobe unevenly distributed across the area of the beam, particularly at theoutside edge of the beam. A concave configuration that has beensuccessful in distributing the light from an LED having or nominallyhaving a lambertian radiation pattern has a rear surface 1102 that isflat except for a shallow depression with a diameter approximately twothirds of the overall diameter of the lens 1100. A rear surface 1102having a concave region of diameter smaller than that of the convexfront surface 1101 but other than two thirds that of the convex frontsurface 1101 can also be made to work. The depth of the depression inthe rear surface 1102 in this lens 1100 is only a few percent of thethickness of the lens 1100. The shape of such a depression in the rearsurface 1102 in the successful lens 1100 is such that the depth of thedepression as a function of radius from the axis of the lens 1100deviated from the depth on axis by an amount proportional to the fourthpower of the radius. This makes the depression in the rear surface 1102essentially flat in its center, but with curvature increasing towardsits edge. It is noted that not all concave configurations will have thebenefits of this configuration. Persons skilled in the art will be ablebest to configure beneficial lenses for their application based on thedescription provided herein, for example, by using ray tracings possiblyassisted by computers and appropriate software.

The forward surface 1101 of the lens 1100 would normally be entirelyconvex, but part of this surface 1101 could be made flat, conical orconcave and the lens 1100 will still work adequately.

The forward surface 1101 may be spherical or an aspheric shape such asellipsoidal, paraboloidal, hyperboloidal, a fraction of a cycle of asinusoid rotated about the axis 1103, or any mathematical combination ofany of these and/or any mathematical combination of a sphere and any ofthese.

A concavo-convex version of the lens 1100 is shown with part of the rearsurface 1102 being flat rather than concave. This flat region may beomitted or substituted with any other shape. The edge of the lens 1100is shown in the form of having the forward surface 1101 and the rearsurface 1102 intersecting with each other, but a lens 1100 can be madewith the forward surface 1101 and rear surface 1102 not intersecting atthe edge. For example, the lens 1100 may have an edge that iscylindrical.

If the lens 1100 is made of acrylic or of another material having arefractive index near 1.5 and the central region of the rear surface1102 is flat, then the distance along the axis 1103 between the frontsurface 1101 and the rear surface 1102 may be equal to the radius ofcurvature of the central region of the front surface 1101. This has beenfound to work well, although it is obvious that a different distancealong the axis 1103 between the front surface 1101 and the rear surface1102 may be found to work adequately. The hemispheric lens 1100 a is aspecial case of a variation of the lens 1100 having a distance along theaxis 1103 between the front surface 1101 and rear surface 1102 that isequal to the radius of curvature of the central region of the frontsurface 1101. The ideal distance along the axis 1103 between the frontsurface 1101 and the rear surface 1102 is likely to be different if thelens 1100 is made of a material having a refractive index other than1.5.

An LED other than one having a lambertian radiation pattern may be usedwith the lens 1100. Lumileds Luxeon LEDs having the “Batwing” radiationpattern tend to produce beams that are brighter at their edges than attheir center, but a variation of the lens 1100 can be made that correctsthis. As noted above, a usable beam has been achieved by placing ahemispheric ½ inch diameter variation of the lens 1100 forward of aLumileds Luxeon LED having the “batwing” radiation pattern.

Any lens 1100 or hemispheric lens 1100 a may have texturing, ridges orfacets on any of its surfaces. Any facets or texturing may be in apattern or may be random. Texturing or facets would be added to the lens1100 or hemispheric lens 1100 a for purposes such as softening orotherwise adjusting the beam produced by the lens 1100 or hemisphericlens 1100 a, or to achieve an attractive appearance of the lens 1100 orhemispheric lens 1100 a.

Referring to FIG. 12, an LED work light 1200 may have its head sectioncomprising a metal channel piece 1202 that comprises side flanges 1202 band a rear portion 1202 a. The LED work light 1200 further comprises oneor more LEDs 101 and a convex lens 1100 forward of each LED 101. The LEDwork light 1200 preferably comprises at least two LEDs 101 and in suchcase would have at least two lenses 1100 with one lens 1100 forward ofeach LED 101. As shown, the one or more convex lenses 1100 are part of atransparent cover/lens assembly 1201. Alternatively, the transparentcover/lens assembly 1201 may be omitted or separate from the one or morelenses 1100. This would require alternative means of mounting the lenses1100. Further alternatively, any lenses 1100 may be omitted anddifferent optics such as any of the optics of FIG. 7 or reflectors maybe used.

Variations of the one or more lenses 1100 include the hemispheric lens1100 a shown in FIG. 11.

The transparent cover/lens assembly 1201 that includes one or morelenses 1100 may be molded. The transparent cover/lens assembly 1201including one or more lenses 1100 may be machined after molding.Machining after molding may be done for purposes such as repair of sinkmarks. Polishing is typically necessary after machining if machining isdone on any optical surfaces of the one or more lenses 1100.

The metal channel piece 1202 can be used as a heatsink for the one ormore LEDs 101. The LEDs 1201 are preferably mounted on the insidesurface 1206 of the rear portion 1202 a of the channel piece 1202. Otherarrangements are possible for heatsinking of the LEDs 101. The positionof the LEDs 101 may be adjusted by placing a metal disc or other planarpiece of metal (not shown) between the LEDs 101 and the inside rearsurface 1206.

The transparent cover/lens assembly 1201 may be attached to the channelpiece 1202 by means of screws 1204 that pass through holes 1203. Agasket (not shown) may be used between the transparent cover/lensassembly 1201 and the channel piece 1202 to achieve watertightness.Other means may be used to attach the transparent cover/lens assembly1201 to the channel piece 1202, such as gluing.

Each of the lenses 1100 preferably concentrate the light from itscorresponding LED 101 into a beam that is 40 to 90 degrees wide and hasan attractive brightness profile such as having an impressively sharpedge. Alternatively, a beam with a sharp edge may be obtained by havingeach lens 1100 of such characteristics and located such that it forms afocused image of a part of each LED 101 such as its chip, its die cup,or the edge of its transparent case. Further alternatively, a washer orother cover with a hole (not shown) can be placed forward of each of theLEDs 101 so that each of the lenses 1100 can produce a beam that is inthe form of an image of the hole that is placed forward of itscorresponding LED 101.

The transparent cover/lens assembly 1201 typically has walls 1205 thatpermit mounting of the transparent cover/lens assembly 1201 with theintegral lenses 1100 sufficiently forward of the LEDs 101. The LED worklight 1200 may have more than one transparent cover/lens assembly 1201that includes at least one convex lens 1100.

The LED work light 1200 would preferably be constructed such that theforward edges of the side flanges 1202 b of the channel piece 1202 arefarther forward than other parts of the LED work light 1200. Thisprotects the other parts of the LED work light 1200 from falls. Such aprotective channel piece may extend the full length of the LED worklight 1200 or it may be confined to a distinct light head section of theLED work light 1200. The side flanges 1202 b may or may not exist overthe entire length of the channel piece 1202. Other arrangements arepossible where a work light can have parts recessed within an outercasing so as to be protected from falls.

The LED work light 1200 typically further comprises parts not shown inFIG. 12 such as wires, one or more resistors or other current limitingcircuitry for the one or more LEDs 101, a power cord or one or morebatteries, and a handle. Variations of the LED work light 1200 can bemade without a handle so as to be used for alternative stationaryapplications such as display case lights.

Referring to FIG. 13, the LED work light 1200 is shown comprising a headsection 1200 a and a handle section 1200 b. The head section 1200 a isshown as having two LEDs 101, although a different number of LEDs 101may be used. For example, a work light similar to the LED work light1200 but having four LEDs 101 with a power rating of approx. 1.2 wattshas performed well in prototype testing. Such LEDs may be incorporatedinto any one of the embodiments described herein.

A different work light similar to the LED work light 1200 of one of theother lights described herein can be made with only one LED 101,especially if the LED 101 is a higher power one such as the LumiledsLuxeon V whose nominal power rating is 5 watts. The work light 1200 andother work lights described herein in some other embodiments provide anLED work light that produces a combination of illumination intensity andillumination coverage area that is not provided by prior LED worklights. At least one LED manufacturer has announced plans to produce in2005 white LEDs that are as efficient as some fluorescent lamps. Ashigher efficiency LEDs become available the LEDs may be incorporatedinto alternate embodiments of work lights described herein or based onthe principles described herein.

As shown, the head section of the work light 1200 comprises the partsshown in FIG. 12, namely an outer casing in the form of a heatsinkingmetal channel piece 1202, any number (two are shown) of LEDs 101, and alens 1100 forward of each of the LEDs 101 and comprised within atransparent cover/lens assembly 1201.

The transparent cover/lens assembly 1201 may be substituted with a flatlens assembly such as the lens assembly (1400 of FIG. 14) if it ismounted over any necessitated spacer or plurality of spacers (not shown)that substitute for the wall regions 1205 of the lens assembly 1201.

As shown, the side flanges 1202 b of the metal channel extend only overthe head section 1200 a and not over the handle section 1200 b.Alternative arrangements are possible, including having the side flanges1202 b extend over the entire length of the LED work light 1200including the handle section 1200 b.

The LED work light 1200 is operable from batteries 1208. Batteryoperation may be included with any of the embodiments described hereinor alternate embodiments based upon the principles described herein.Battery operation is not limited to a work light having a head sectionas described above for the work light 1200. The work light 1200 may havea removable battery pack 1207 that contains one or more batteries 1208.Alternatively, batteries 1208 may be permanently installed. Thebatteries 1208 may not be contained within a battery pack 1207. Furtheralternatively, the LED work light 1200 may be constructed so as toreceive power through a cord (not shown) rather than from includedbatteries 1207. The battery pack 1207 may but does not necessarilyfurther comprise a charging circuit 1209 and one or more indicator lamps1210. As shown, the battery pack 1207 may have a battery pack casing1207 a which may be made of plastic and may be molded but may be made ofa different material such as steel or another metal. Alternatively, abattery pack 1207 may merely comprise a plurality of batteries 1208 heldtogether with tape or plastic film or glue or by other means. As shown,the battery pack casing 1207 a has ridges 1207 b to hold the chargingcircuit 1209. Other means may be employed to mount any charging circuit1209 such as screws, rivets, or glue. If a charging circuit 1209 isincluded in the LED work light 1200, it may be located on the outside ofor not be a part of the battery pack 1207.

The LED work light 1200, as shown, preferably has a circuit board 1211that includes current regulating circuitry or other current limitingmeans typically required for proper operation of the LEDs 101.

The circuit board 1211 is shown as being between the handle section 1200b and the LEDs 101, but this is not a limitation on the location of thecircuit board 1211.

Additional circuitry that prevents operation of the LED work light 1200under unfavorable conditions may be included in the circuit board 1211or elsewhere. Such additional circuitry may include means to detectexcessive temperature and to shut down the LED work light 1200 ifexcessive temperature is detected. Such additional circuitry may includemeans to detect low battery voltage and means to shut down the LED worklight 1200 if excessively low battery voltage typical of batteries 1208being nearly discharged is detected. Circuitry to provide other featuressuch as a paging feature may also be included in the circuit board 1211or elsewhere in the LED work light 1200.

Again, the circuit board 1211, regulating circuit and additionalcircuitry could also be applied to the other work lights describedherein and to alternate embodiments based upon the principles describedherein. The ballast circuit 800 previously described herein is anexample of the regulating circuitry that may be included on circuitboard 1211.

A switch 1212 is preferably included in any LED work light, for examplethe LED work light 1200, in order to turn the work light on and off. Inthe work light 1200 the switch 1212 may be attached to the inner surfaceof either side flange 1202 b of the metal channel piece 1202, althoughother arrangements are possible.

The LED work light 1200 typically has wires 1213 connected to such partsas the LEDs 101, the batteries 1208, the charging circuit board 1209,the circuit board 1211 and the switch 1212. If the batteries 1208 or thebattery pack 1207 or any other parts requiring electrical connectionsare removable, then connectors (not shown) would preferably be added toremovable parts in order to disconnect removable parts from wiring orother conductors that connect to such removable parts.

If the batteries 1208 in the battery pack 1207 are rechargeable, thenthe battery pack 1207 would preferably have one or more chargingconnectors such as charging jacks 1214. Any charging connectors may beof a different form such as springs. Charging connectors may connect tothe charging circuit 1209 via charging wires 1215. Other arrangementsare possible, such as having any charging connectors soldered to orotherwise mounted on the charging circuit 1209. Any battery pack 1207may include one or more charging connectors such as charging jacks 1214even if the charging circuit 1209 is located outside the battery pack1209 or omitted.

Any charging connectors such as charging jacks 1214 may be protectedfrom dirt, corrosion, liquids, etc. by a removable cover (not shown).The charging connectors such as charging jacks 1214 may be recessed sothat such a protective cover can be a screw-on lid that may have ano-ring. Alternative protective covers are possible such as a rubber cap.

Again, the connectors described above can be applied to otherembodiments of work lights based upon the principles described hereinwherein removable components are used.

Work lights such as the LED work light 1200 may have a handle cover 1216that may be made of rubber. Purposes of a rubber handle cover includeachieving greater comfort of holding the LED work light 1200, reductionof slipperiness of the handle section 1200 b if it gets wet, or aselectrical insulation or for protecting from impacts parts of the LEDwork light 1200 that the handle cover 1216 would cover. The handle cover1216 may be removable for purposes such as permitting removal of anyremovable batteries 1208 or removable battery pack 1207. Such handlecovers may be used on embodiments of the present invention other thanhaving the arrangement shown.

Referring to FIG. 14, a lens assembly 1400 having lenses 1100 can beused in various embodiments of the work lights described herein oralternate work lights based upon the principles described herein in lieuof separate individual lenses. The lens assembly 1400 comprises agenerally planar plate 1401 and the lenses 1100 in a single plasticpiece that may be molded. The plastic plate 1401 may have screw holes1402 or other provisions for mounting. The lenses 1100 may have any ofthe above characteristics, including but not limited to any of theoptical characteristics, of the lenses 1100 or 1100 a of FIG. 11described above.

Although the lens assembly 1400 would preferably be a single piece ofplastic that is molded and may be machined afterwards, it can be made ofa different material such as glass or it may be made in a different waysuch as assembling the lenses 1100 into the planar plate 1401.

Although the plate 1401 is generally planar, it is not required to use agenerally planar plate.

Referring to FIG. 15, a work light 1500 can be constructed like the LEDwork light 1200 shown in FIG. 13, except a receiving coil 1501 forinductive charging can be used in lieu of one or more charging jacks orother contacts.

The receiving coil 1501 supplies power to the charging circuit board1209. In order to do so, the receiving coil 1501 receives power from atransmitting coil 1502 that is within a charging station 1503. Thecharging station 1503 preferably has a power cord 1504, a power supplysection 1505 and a transmitting circuit 1506 such as a high frequencyoscillator to supply power to the transmitting coil 1502. Thetransmitting circuit 1506, may operate at an audio frequency or at anultrasonic frequency such as a frequency that may be considered a radiofrequency. Having the transmitting circuit 1506 operate at a frequencylower than audio frequencies is foreseen to be impractical but notimpossible. Wires 1507 would typically be necessary for purposes such asconnecting the power supply 1505 or the transmitting coil 1502 to thetransmitting circuit 1506.

The receiving coil 1501 and the charging circuit board 1209 are shownwithin the battery pack 1207, but other arrangements are possible suchas having either or both of the receiving coil 1501 and charging circuitboard 1209 located elsewhere in the work light 1500.

The battery pack 1207 has a coupling surface 1207 c and the chargingstation has a coupling surface 1503 a that are shown as flat andadjacent to their respective coils 1501 and 1502. No magnetic corematerial is shown, however addition of a magnetic core to either of orboth of the transmitting coil 1502 or the receiving coil 1501 canimprove transfer of power from the transmitting coil 1502 to thereceiving coil 1501. Such magnetic cores may be made of ferrite,powdered iron or other powdered magnetic material, a solid magneticmaterial such as high silicon steel, or an assembly of laminations orwires or other narrow or thin pieces of a magnetic material such as“transformer steel”, “high silicon steel” or iron.

Any magnetic cores may be arranged to exist inside or outside of eitheror both of the transmitting coil 1502 and receiving coil 1501. Amagnetic core may have parts existing both inside and outside of any ofthe coils 1501/1502. Examples of such a core are the “E core” and the“pot core”, which have both a region intended to extend through a coil(known as the “center leg”) and a region intended to surround a coil(sometimes known as “outer legs”, especially if the core is an “Ecore”).

It may be found beneficial to have a piece or assembly of magneticmaterial passing through and/or around both the transmitting coil 1502and the receiving coil 1501. This will typically necessitate having thecoupling surfaces 1207 c/1503 a other than flat so as to permit such apiece or assembly of magnetic material to pass through and/or aroundboth coils 1501/1502 while being contained within the battery pack 1207or the charging station 1503.

Advantages of inductive charging include lack of corrosion and lack ofneed to clean charging jacks or charging contacts, ease of watertight orliquid-tight or explosion proof construction, and a more attractiveappearance.

Most other parts within the work light 1500 are shown as identical tothose in the LED work light 1200 of FIG. 13. Parts of the work light1500 that are shown the same as corresponding parts of the LED worklight 1200 are the LEDs 101, head section 1200 a, handle section 1200 b,lenses 1100 in a lens assembly 1201 that also has walls 1205, metalchannel piece 1202 having side flanges 1202 b and a rear flat section1202 a with an inner surface 1206 suitable for mounting the LEDs 101 on,screw holes 1203, screws 1205, battery pack 1207, batteries 1208,charging circuit 1209, indicator lamp 1210, circuitry 1211, switch 1212,and wires 1213. Other arrangements will be evident to those skilled inthe art based upon the principles described herein.

Inductive coupling is not the only possible method for having a chargingstation 1503 recharge batteries in a work light 1500 or a battery pack1207. For example, power can be transmitted capacitively throughinsulating surfaces by applying voltage at a high frequency to metalplates or other conductors having significant area. Both the receiverand the transmitter typically require two conductors for capacitivecoupling, and each of these conductors that are associated with thetransmitter would be in close proximity to corresponding conductors inthe receiver. Alternatively the transmitter and the receiver eachrequire only one conductor for capacitive coupling if the transmitterand receiver each also have a direct connection to each other, such asvia a metal part of their outer casings. By further example, a chargingstation 1503 can transfer power to a work light 1500 or to a batterypack 1207 by further alternative means, such as a microwave beam, sound,or light or ultraviolet or infrared. The charging station 1503 may havea high power infrared LED (not shown) that irradiates one or morephotovoltaic cells (not shown) in the work light 1500 or in the batterypack 1207. Any photovoltaic cells may utilize light sources other thanone in the charging station to achieve some recharging of batteries1208, for example ambient light, sunlight, or an electric lamp of a typenormally used for other purposes such as a desk lamp or a larger andless portable work light.

As an even further example of alternative means to transfer power from acharging station 1503 to a work light 1500 or a battery pack 1207, thecharging station 1503 can have a motor (not shown) and the work light1500 or the battery pack 1207 can have a generator (not shown) that eachhave magnets (not shown) attached to their shafts so that the motor canturn the generator without direct mechanical contact.

Inductive coupling or coupling by any of the above alternative meansthat avoid or eliminate any or all direct electrical contacts areforeseen to be beneficial for LED lights generally whether or not theyhave a handle, whether or not they have a beam width of 40 to 90degrees, and whether or not any of their LEDs are of a type thattypically requires heatsinking. Power transfer by means avoiding directelectrical contact may benefit by a light lacking rechargeablebatteries, such as a work light that is powered by an external powersource such as AC line voltage while having a severe requirement ofbeing insulated from said external power source, whether or not saidlight uses LEDs to produce light.

Referring to FIG. 16, an LED work light 1600 can be operated whilemounted on a tripod 1601. The tripod-mounted light 1600 is preferablyable to continue operating if removed from the tripod 1601, andpreferably has one or more rechargeable batteries 1611. The rechargeablebatteries 1611 may or may not be removable from the LED work light 1600.The LED work light may alternatively have non-rechargeable batteries orno batteries at all.

Preferably, the tripod 1601 includes a charging station 1602 thatrecharges the one or more rechargeable batteries in the work light 1600.The charging station 1602 preferably receives power from a line cord1603 that has a plug 1604. The charging station 1602 may alternativelyreceive power from alternative sources such as a low voltage DC externalpower supply such as an automotive battery charger, or an automotivebattery. As an alternative to this arrangement, the LED work light 1600may receive power directly from the line cord 1603.

The LED work light 1600 may be operable while any rechargeable batteries1611 are being recharged. This can be accomplished, for example, byhaving the charging station 1602 supply a specific voltage that issuitable for charging batteries of a type that can be charged byapplying a specific voltage, such as lead acid or lithium ion. Lead acidbatteries can be charged by applying a voltage of approximately 13.5 to14.4 volts per cell whether or not a load is connected to the batteries.

The tripod 1601 preferably has three legs 1605. The tripod preferablyincludes means to adjust the position and orientation of the work light1600, such as but not limited to a rod 1606 that may have teeth orridges 1606 a and an engaging and associated height adjustment knob1607, a tilting joint 1608, and/or a locking knob 1609 in any tiltingjoint 1608. Locking knobs 1609 and/or adjustment knobs similar to theheight adjustment knob 1607 and/or other adjustment means and/or otheradjustment locking means may be incorporated in the tripod 1601.

Although the LED work light 1600 is shown as mounted on a tripod 1601,it can be mounted on a stand other than a tripod. All features describedof the tripod 1601 can be included in a stand other than a tripod. Forexample, the stand can have four legs instead of three legs 1605. Aswill be evident to those skilled in the art, the work light 1600 will bemounted to the tripod 1605 or other stand by a coupling such as athreaded pin on the tripod 1605 or other stand and a threaded receptacleon the work light 1600. A threaded receptacle is a form of accessorymount on the work light 1600. The other work lights described herein maybe provided with an accessory mount to similarly couple with a tripod1605 or other stand. As will be evident to those skilled in the art theaddition of an accessory mount to the work lights described herein mayrequire some modification to the work lights while remaining within thescope of the principles described herein. The accessory mount may beused with other accessories or be located elsewhere on the work light.Some additional accessories and alternative locations will be laterdescribed herein.

The LED work light 1600 or other embodiments may have but are notrequired to have a motion sensor or other human presence detector 1610.Such a motion sensor or human presence detector 1610 may be but is notnecessarily of a passive infrared type or an ultrasonic type. The motionsensor or other human presence detector 1610 may include or beassociated with circuitry (not shown) that dims or shuts down the LEDsin the LED work light 1600 when no people are close to the LED worklight 1600 to benefit from illumination by the LED work light 1600.Benefits of such a motion sensor or other human presence detector 1610include minimizing aging of LEDs and/or discharge of batteries in theLED work light 1600. This may permit operating LEDs within the LED worklight 1600 at a higher power than is otherwise possible withoutexcessive LED aging or excessive discharge of any included batteries.

The benefits of automatic dimming or automatic shutdown that resultsfrom absence of people may be significant in LED lights whether or notsuch LED lights are tripod mountable, whether or not their LEDs are of atype that typically requires heatsinking, whether or not such LED lightsproduce a beam that is 40 to 90 degrees wide, and whether or not suchLED lights have a handle.

Referring to FIG. 17, a rechargeable LED work light 1700 having aremovable battery pack identical to a second battery pack 1701 can berecharged in a charging station 1702. The charging station may be ableto recharge both the rechargeable LED work light 1700 and the secondbattery pack 1701 simultaneously. Alternatively, the charging station1702 may give priority to recharging a rechargeable LED work light 1700over a second battery pack 1701 if both are present and the batterieswithin the LED work light 1700 require charging. The charging station1702 would charge the second battery pack 1701 if the second batterypack 1701 is present and requires charging and the rechargeable LED worklight 1700 is absent or charged.

As shown but not required, the rechargeable LED work light 1700 may fitinto an associated charging nest 1703 in the charging station 1702 whilethe second battery pack 1701 fits into a smaller associated chargingnest 1704 in the charging station 1702. The charging nest 1703 may havea sensor 1703 a such as a switch that is actuated by presence of therechargeable LED work light 1700 for use in giving priority to chargingthe rechargeable LED work light 1700 over a second battery pack 1701.

The charging station 1702 preferably has circuitry 1705 that may includecircuitry that is necessary for proper battery charging and circuitrythat is necessary for any prioritizing of charging a rechargeable LEwork light 1700 over charging of any second battery pack 1701.

The charging station 1702 preferably receives power through a cord 1706that includes a plug 1707 that is suitable to plug into an AC linevoltage outlet. Alternatively, the charging station 1702 may receivepower from a source of low voltage DC such as an automotive cigarettelighter socket, an automotive battery or an automotive battery charger,in which case the charging station 1702 may have the cord 1706 includeclips or a plug 1707 that can clip to an automotive battery or plug intoan automotive cigarette lighter socket. An external power supply thatprovides a DC voltage of essentially 12 or 12-14 volts from line voltageAC and that has an automotive cigarette lighter socket can be founduseful for supplying power to the charging station 1702 if the chargingstation 1702 is to be powered by low voltage DC.

It is to be noted that some nickel metal hydride batteries can berecharged in as little as 15 minutes and there are chargers for suchbatteries to recharge them that quickly. The charging base 1702 may beconstructed so as to recharge the batteries in the rechargeable worklight 1700 in approximately half an hour or less so that a user of therechargeable work light 1700 can have it fully recharged during a lunchbreak. The charging base 1702 may or may not recharge the second batterypack 1701 as quickly as it can recharge the rechargeable LED work light1700.

A charging station that can charge rechargeable batteries within acordless appliance and also a second set of batteries outside theappliance can be beneficial even if the appliance is not one of theembodiments of the present invention described herein. LED work lightscan benefit from such a charging station whether or not they have LEDsthat typically require heatsinking, and whether or not they produce abeam that is 40 to 90 degrees wide. LED lights other than work lightswith handles, such as LED lights intended to be attached to headgear,may also benefit from such a charging station whether or not they haveLEDs that typically require heatsinking and whether or not they producea beam that is 40 to 90 degrees wide.

Cordless tools and cordless lights such as the rechargeable LED worklight 1700 can be lost in cluttered work areas or large work areas. Therechargeable LED work light 1700 can benefit from a paging system thatcauses such lost items to produce an audible signal and/or a visiblesignal or other alarm when one has to find them.

The rechargeable LED work light 1700 is shown having a circuit board1708 that includes an electronic ballast 1709. The typically necessarywiring in the rechargeable LED work light 1700 is not shown.

The rechargeable LED work light 1700 is shown as having a pagingreceiver 1710 with a receiving antenna 1711. This permits paging the LEDwork light 1700 from a paging transmitter 1714 that is shown as beingcomprised in the charging station 1702. The paging transmitter 1714 isshown with an associated transmitting antenna 1712 and a pagingpushbutton 1713.

The paging transmitter 1714 and associated paging pushbutton 1713 andtransmitting antenna 1712 are not necessarily included in the chargingstation 1702 as shown, but may alternatively be comprised in a separatepaging transmitter unit.

When the paging pushbutton is depressed, the paging transmitter 1714transmits a paging signal that is received by the paging receiver 1710.When the paging receiver 1710 receives a paging signal, it produces anaudible signal and/or a visual signal or other alarm so that therechargeable LED work light 1700 can be located. Such an audible signalmay be produced by a piezoelectric transducer. Visual signaling may beaccomplished by the LEDs 101 or by a separate light source provided forpaging purposes.

Preferably the visual signal would include flashing of the light sourceto attract the attention of the searcher. Flashing of the signalprovides the additional benefit of identifying the work light so as todistinguish it from other light sources that may be in use.

The paging system may include an identification system such thatmultiple work lights within a single environment may be differentiatedfrom one another. Such an identification system may include operatingthe work lights receivers and their respective transmitters on differentfrequencies. Alternatively, a code could be transmitted by the pagingtransmitter that is recognized by the appropriate paging receiver. As anexample, a key fob transmitter and receiver pair could be used. Onetransmitter could be set to page multiple work light receiversindependently. Such a receiver could be built into a single centralstation with multiple buttons for paging different lights. A chargingstation could be built with multiple storage and/or charging bays forwork lights. Such a charging station could include a central pagingstation. Separate paging activators (such as button switches) could beprovided on the central paging station for each work light on the pagingsystem. Each paging activator could be visibly associated with adifferent one of the storage and/or charging bays of a charging station.Visible indicators (for example name tags or an alphanumeric symbol)could be used to identify a paging activator and work light pair. Such asystem could be used quickly to identify which work light is which in acommon environment. This can avoid or resolve disputes. It can alsoassist in inventorying work lights. It can also assist in maintence ofwork lights if, for example, batteries are to be changed on a givenschedule for each light. If protective circuitry to prevent therechargeable LED work light 1700 from operating with excessivelydischarged batteries or under other adverse conditions is provided, thena preferred arrangement of circuitry in the rechargeable LED work light1700 preferably has the paging receiver 1710 not disabled by suchprotective circuitry. For example, the paging receiver 1710 may includean auxiliary battery 1715. Such an auxiliary battery 1715 may bearranged to be recharged whenever the rechargeable LED work light 1700is recharged. Alternatively the auxiliary battery 1715 may be rechargedfrom the battery pack within the rechargeable LED work light 1700.Further alternatively, the auxiliary battery 1715 may be recharged by asolar cell (not shown).

As an alternative to having an auxiliary battery 1715, the rechargeableLED work light 1700 may have the paging receiver 1710 bypass anyprotective circuitry intended to disable operation of the rechargeableLED work light 1700 under adverse conditions such as excessivelydischarged batteries. This can be acceptable since paging therechargeable LED work light 1700 is not expected to worsen significantlyan excessively discharged condition of any batteries nor significantlyworsen any other adverse conditions such as any excessive temperature.

The paging transmitter 1714 and paging receiver 1710 are shown with therespective transmitting antenna 1712 and receiving antenna 1711 in orderto respectively transmit and receive a radio signal.

Alternatively, the paging transmitter 1714 may transmit and the pagingreceiver 1710 may receive a signal other than a radio signal, such as anultrasound signal or an infrared signal via appropriate transducers inlieu of the transmitting antenna 1712 and receiving antenna 1711.

Any transmitting antenna 1712 and/or receiving antenna 1711 may bedifferent from the ones shown. For example, a wire being used foranother purpose within the rechargeable LED work light 1700 may be usedas the receiving antenna 1711. By further example, a conductivestructural part, a heatsink or a reflector within the rechargeable LEDwork light 1700 may be used as the receiving antenna 1711.

In lieu of requiring the paging transmitter 1714, the paging receiver1710 may be constructed so as to be actuated by receiving a signal thatcan be produced by means other than the paging transmitter 1714. Forexample, the paging receiver 1710 may be constructed so as to beactivated by hand claps, a police whistle, a camera flash or blinking ofambient lighting.

Paging systems are particularly useful with compact LED work lights thatcan be easily lost within a crowded work environment such as anautomotive garage. Paging systems are also particularly useful whenworking in dirty environments where the work light can be coated withoil, grease or other substances that tend to make the work light hard todistinguish from other devices in the environment. An audible signal isparticularly useful in an environment where the work light may be placedin a drawer or other non-visible storage area. Again, this isparticularly useful for compact LED work lights that can be easilystored away or hidden. A search for a work light can be conducted byactivating the signal, listening for the signal, moving in the directionof the signal, and opening access to any storage areas, if required,until the work light is located. A visual signal is particularly usefulin a noisy environment, such as an automotive garage. A combination ofboth visual and audible signals is useful for both noisy environmentsand environments where light may not be distinguishable. The pagingsystem can have independent activation means for different signals.

LED work lights can benefit from a paging system whether or not theyhave LEDs that typically require heatsinking, and whether or not theyproduce a beam that is 40 to 90 degrees wide. LED lights other than worklights with handles, such as LED lights intended to be attached toheadgear, may also benefit from a paging system whether or not they haveLEDs that typically require heatsinking and whether or not they producea beam that is 40 to 90 degrees wide.

Referring to FIG. 18, the LED work light 1200 described above and shownin FIG. 13 may be constructed so as to be able to be operated while itsbatteries 1208 are being recharged. The LEDs 101, lenses 1100, and allparts 1200-1215 are described above in the description of the LED worklight 1200 shown in FIG. 13, although some parts may need to be chosen,disposed and arranged such as to achieve recharging of the batteries1208 while the LED work light 1200 is operating.

In order for the batteries 1208 to be recharged, the charging circuitry1209 must receive power from an external power source, for example byreceiving either line voltage AC or low voltage DC through a power cord1804 that has a plug 1805. The power cord 1804 would preferably, asshown, supply power to an adapter 1800. The plug 1805 is shown as beingof a type to be plugged into an outlet that supplies line voltage AC,although different connection means such as clips or a different plugmay be used. For example, the plug 1805 may be a plug that plugs into anautomotive cigarette lighter, so that the adapter receives low voltageDC, such as essentially 12 or 12-14 volts DC.

The adapter 1800 is shown as having electrical adapting means 1803 thatmay comprise a transformer and may further comprise a rectifier and/or afilter capacitor. This electrical adapting means 1803 is typicallynecessary in order to receive line voltage AC and supply power at avoltage that is suitable to be supplied to the charging circuit 1209.Alternatively, the charging circuit 1209 may be capable of receivingline voltage AC, or the charging circuit 1209 may have the capability ofcharging the batteries 1208 from either line voltage AC or low voltageDC. If the charging circuit 1209 is capable of receiving power directlyfrom the power cord 1804, then the electrical adapting means 1803 is notnecessary and the adapter 1800 would preferably merely be a fitting thatattaches the power cord 1804 to the LED work light 1200. Furtheralternatively, not only any necessary electrical adapting means 1803 butalso the charging circuit 1209 can be comprised within the adapter 1800in lieu of having the charging circuit 1209 comprised within the LEDwork light 1200.

Regardless of specific arrangements, an LED work light such as the LEDwork light 1200 may receive power from one adapter 1800 with anassociated power cord 1804 and plug 1805 that receive line voltage AC,and the same LED work light can also be operated from a differentversion of the adapter 1800, power cord 1804 and plug 1805 or otherconnection means that receive low voltage DC such as essentially 12 or12-14 volts DC. Alternatively, it is possible that the plug 1805 can bedetachable from the power cord 1804 so that a different version of theplug 1805 can be used, especially if the LED work light is capable ofutilizing both line voltage AC and low voltage DC.

Any lights that can utilize low voltage DC may be able to utilizeessentially 12 or 12-14 volts DC, a different voltage of DC, or both ora wide range of voltages of DC.

The LED work light 1200 may be operated while its batteries 1208 arebeing recharged. Such an arrangement is easy to accomplish if thebatteries 1208 are lead acid batteries or lithium ion batteries, sincesupplying a specific voltage to such batteries will recharge suchbatteries while they have a load connected to them. In addition tosupplying a fixed voltage, it may be necessary to use current regulationor other current limiting means to avoid having the batteries 1208conduct excessive current should application of the voltage necessaryfor full charge otherwise cause excessive current to flow through thebatteries 1208. It is preferable to have adequate current tosimultaneously power the LEDs 101 and recharge the batteries 1208.Alternatively, part of the charging circuit 1209 or alternativeadditional circuitry may provide means to have the LEDs 101 receivepower other than directly from the batteries 1208 when the adapter 1800is receiving power and attached to the LED work light 1200. Furtheralternatively, the charging circuitry may be able to monitor thetemperature or an electrical condition of the batteries 1208 while theyare being charged, in order to properly charge any nickel cadmium ornickel metal hydride forms of the batteries 1208 while a load such asthe LEDs 101 is connected to them.

Although the LED work light 1200 benefits from an ability to be operatedwhile receiving power from an external source of power to recharge itsbatteries 1208 it is also able to be operated when the adapter 1800 andpower cord 1804 are not attached to the LED work light 1200.

The adapter 1800 may comprise connecting prongs 1801 and springs 1802 inorder to supply power to the charging jacks 1204 or alternative chargingconnectors that the LED work light 1200 preferably has for receivingpower. Other means can be comprised in the adapter 1800 for connecting apower cord 1804 to an LED work light 1200.

Other arrangements will be evident to those skilled in art to rechargethe batteries 1208 while the LED work light 1200 is being used. Forexample, a charging station may hold the LED work light 1200 in aposition where it can be used while recharging the batteries 1208.

An LED work light with rechargeable batteries, whether or not the LEDwork light has LEDs of a type that typically requires heatsinking andwhether or not the LED work light produces a beam that is 40 to 90degrees wide, can benefit from being able to be operated whether or notits batteries are being recharged. Any LED work light with rechargeablebatteries can benefit from being able to receive power from a detachablepower cord whether or not the LED work light has LEDs of a type thattypically requires heatsinking and whether or not the LED work lightproduces a beam that is 40 to 90 degrees wide.

An alternative embodiment of an LED work light 1200 that can utilizepower of different voltages through different adapters 1800 andassociated power cords 1804 may lack batteries 1208 and chargingcircuitry 1809, in which case it can only be operated while an adapter1800 and associated power cord 1804 are attached. Such an LED work lightmay or may not produce a beam that is 40 to 90 degrees wide and may ormay not have LEDs of a type that typically requires heatsinking. Such anLED work light may use one detachable adapter in order to utilize linevoltage AC and it may use a different detachable adapter to utilizepower of a different voltage such as 12 or 12-14 volts DC or other lowvoltage DC.

Referring to FIG. 19, an LED work light 1900 having a power cord 106further comprises means to allow the cord 106 to rotate within the LEDwork light 1900, or for the LED work light 1900 to rotate around thecord 106. This eliminates or at least reduces the occurrence andseverity of twisting of the cord 106 that results from rotating the LEDwork light 1900 over time. Work lights can benefit from such means toallow rotation of the cord even if they use one or more light sourcesother than the LEDs 101 shown.

As shown, such means to permit rotation may use two rotatable contactssuch as a rotating tip contact 1903 and a slip ring 1904, which arecontacted by their respective brushes 1905, 1906. The tip contact and isconnected to a first wire 1901 and the slip ring 1904 is connected to asecond wire 1902 that run through the power cord 106. Not shown forclarity is the insulation that the wires 1901, 1902 typically have overmost their length. The tip contact brush 1905 and the slip ring contactbrush 1906 are connected to wires 1907, 1908 that are connected to acircuitry assembly 1905 that includes current limiting means typicallyrequired by the LEDs 101.

The power cord 106 may be connected to a “wall transformer” powersupply. Alternatively, the power cord 106 may have a plug to receiveline voltage AC, or a different plug such as one that fits into anautomotive cigarette lighter socket.

The brushes 1905, 1906 may be metal or they may be made of a differentconductive material. Alternatively, the brushes 1905, 1906 may beassemblies having springs and pieces of carbon that make contact withrotating contacts.

The LED work light 1900 is shown as being otherwise similar to the LEDwork light 900 of FIG. 9, comprising a head section 103, a handlesection 102, a heatsink 104, and wires 109 connected to the LEDs 109.

The tip contact 1903 and the slip ring 1904 are shown as mounted on atube 1909. Also shown as mounted on the tube 1909 are rotating guides1910 which slide against stationary guides 1911. The stationary guidesare shown as mounted on the interior surface of the handle section 102.Any rotating guides 1910 may be force-fitted over the tube 1909, gluedto the tube 1909, otherwise attached to the tube 1909 or comprisedwithin the same piece of material as the tube 1909. Likewise, thestationary guides 1911 may be force fitted into the handle section 102;glued to the handle section 102, attached in another manner to thehandle section 102, or comprised in the same piece of material as thehandle section 102.

The rotating guides 1910 and the stationary guides 1911 may be made ofpolytetrafluoroethylene or of any other material that has suitably lowfriction and suitably high resistance to wear. Alternatively, any of therotating guides 1910 and the stationary guides 1911 may be made of adifferent material but coated with a suitable material such aspolytetrafluoroethylene or molybdenum disulfide.

Arrangements other than the one shown may be used. For example, bearingsand/or bushings may be added or used in place of brushes. Bearings maybe fitted within or mate against ridges, grooves, cups and/or cones. Anybearings and/or bushings may or may not conduct current.

In lieu of the tip contact 1903, a second slip ring may be used.

By further example, the brushes 1905, 1906 may be arranged axially so asto contact two concentric washers or a washer surrounding a disc thatare used in lieu of any slip rings 1904 and non-disc-shaped contacts1903. Alternatively to a washer arranged with a disc or a smaller washerwithin it, two washers may be mounted onto different parts of the tube1909. As an even further example, any rotating contacts may be conicalrather than cylindrical or in the form of discs and/or washers.

Like other embodiments that have power cords, the LED work light 1900may have added to it means to allow the power cord 106 to be detachable,described above and shown in FIG. 18.

Referring to FIG. 20, and LED work light 2000 having a power cord 2001can benefit from the power cord 2001 being retractable into a reel 2002.A second power cord 2003 is connected to the reel 2002 and has a plug2004 to receive power from a suitable receptacle. The reel 2002 includesnecessary means such as slip rings, a spring and a ratchet (not shown)to permit a user of the LED work light 2000 to alternately pull the LEDwork light 2000 into an extended position and to cause the LED worklight 2000 to be retracted by pulling on the LED work light 2000.

The reel 2002 includes a normally closed switch 2005 with an extensionlever 2006 that is actuated by a ball 2007 on the power cord 2001 whenthe LED work light 2000 is retracted. The ball 2007 can be moved alongthe power cord 2001 in order to set the minimum length of the portion ofthe power cord 2001 that normally exists outside the reel 2002.

The power cord 2001 may be threaded over one or more pulleys 2008 asshown. As shown, the reel 2002 may be mounted by means of a reelmounting bracket 2009 and the pulley 2008 may be mounted by means of apulley mounting bracket 2010, but other arrangements are possible.Bearings and/or bushings (not shown) may be included in the reel 2002and/or any pulleys 2008.

The above scheme has already been used with work lights that have a 13watt compact fluorescent lamp as the light source. However, an LED worklight 2000 can benefit from the reel 2002 and its switch 2005, whetheror not the LED work light produces a beam having a width of 40 to 90degrees, and whether or not the LED work light 2000 has LEDs thatrequire heatsinking means.

The plug 2004 may be of a type that is intended to plug into a linevoltage AC outlet. Alternatively, the plug 2004 may be of a type thatfits into an automotive cigarette lighter socket. Further alternatively,the second power cord 2003 may have in lieu of the plug 2004 alternativemeans of receiving electrical power, such as clips that clip onto abattery.

Any current limiting circuitry and/or other circuitry that the LED worklight 2000 requires may be comprised in the LED work light 2000, withinor on the reel 2002, or within the plug 2004. For example, the plug 2004may be a “wall transformer” that contains circuitry such as a currentregulator.

The reel switch 2004 as opposed to a switch on work lights such as theLED work light 2000 is finding favor with workplace safety agencies,since lack of a switch on the LED work light 2000 reduces the risks ofelectric shock and ignition of flammable or explosive vapors. The lackof a switch on work lights is favored by workplace safety agencies evenif the work lights are of a construction that does not eliminate a needfor labels warning to use only in environments that are dry and lackingflammable and/or explosive vapors.

Means other than shown in FIG. 20 can be used to accomplish switching ofa work light by pulling it or allowing it to be retracted. Furthermore,alternative means of switching a work light lacking a switch on its heador handle are possible, such as radio, ultrasound or other acoustic, orinfrared or other optical means of remote control. Alternative switchingmeans of switching a work light can include a position switch or amagnetic switch or other switch such as an optical switch in the lighthead or its handle, so that the work light can be turned off by leavingit in a position or in a location where it is normally not required tobe operating. Any position switch may be, by example and not limitation,a “tilt switch”, a mercury switch, a combination of mercury switches.

Referring to FIG. 21, an LED work light 2100 can have a hook that can bepositioned straight up, forward from straight up, rearward from straightup, rotated, or retracted into casing (not labelled in FIG. 21 forclarity, see reference numeral 2200 for example in FIGS. 22-24). Asshown, the hook 2101 can be moved rearwards and downwards and rotatedsuch as to fit into a suitable recess in the form of depression 2103 inrear casing piece 2102. The lower part of the hook is a ball 2104 thatfits into a hook clip 2105 that is mounted in the rear casing piece2102.

The ball 2104 and the remainder of the hook 2101 are preferably madefrom the same piece of material. Alternatively, the ball 2104 can befitted over or otherwise added to the hook 2101. The hook 2101 and theball 2104 are preferably made of injection molded thermoplastic.Alternatively, other materials such as a metal may be found suitable forthe hook 2101 and the ball 2104. Further alternatively, the ball 2104,and also the hook 2101 if made from the same piece of material as theball 2104, may be made of polytetrafluoroethylene or other materialselected to minimize wear.

Like the ball 2104, the hook clip 2105 may be made of injection moldedthermoplastic or other materials such as metal orpolytetrafluoroethylene.

Other external structural parts of the work light 2100 are the frontcasing piece 2106 and the bottom casing piece 2107 a. The work light2100 may further comprise an insert 2120 that has a logo or otherinformation printed on it. This insert 2120 is preferably plastic butmay be made of an alternative material such as metal. The insert 2120may have an adhesive backing or it be affixed to the casing 2200 by anadhesive material such as glue, or the insert 2200 may be otherwiseretained in place, for example, by screws, a cover or the like.

A bumper, not shown, such as those that have been described with respectto other embodiments, may be overmolded on the casing or may also beincluded as a separate part that is sandwiched between the front casingpiece 2103 and rear casing piece 2102.

The bottom casing piece 2107 a receives a battery pack 2107 comprisingthis bottom casing piece 2107 a and batteries 2108. Not shown areelectrical connections, such as wiring to deliver electrical power fromthe batteries 2108, and a charging jack for recharging the batteries2108.

The work light 2100 further comprises an LED board 2109 and a singlepiece lens assembly 2111.

The lens assembly 2111 preferably has convex lens elements 2119 in thesame manner as single piece lens assemblies described previously. LEDs2110 are mounted on the LED board 2109. Preferably the LED board 2109 isa metal core printed circuit board and the LEDs 2110 are of a type thatis intended to be reflow soldered onto metal core printed circuitboards. Metal core printed circuit boards are desired for their abilityto conduct heat from the LEDs 2110. The LED board 2109 is mounted to aheatsink 2112. This provides thermal connection from the LEDs 2110 tothe heatsink 2112. Other arrangements are obviously possible, such asmounting alternative LEDs by alternative means to an alternative LEDboard. For example, LEDs of Luxeon Star type by Lumileds can be screwedonto an aluminum LED board or further alternatively directly to theheatsink 2112. Alternatively, in some circumstances, particularly withlower ambient temperature, adequate air flow, and a small number ofLEDs, and where the maximum recommended LED power is not very high bytoday's standards, for example at near or less than 1.25 watts in manycases, the only heatsink that may be necessary is the metal core printedcircuit board that come with high power LEDs, with the LEDs attached tothese boards by the LED manufacturers or suppliers, such printed circuitboards are heatsinks for the purposes described herein.

The rear casing piece 2102 has openings in the form of slots 2113 sothat heat can be transferred to ambient air outside the casing 2200 fromthe heatsink 2112 by convection and/or by conduction of heat. The slots2113 allow the heatsink 2112 to be smaller in size than would otherwisebe required, particularly where the casing 2200 material is generallynot considered to be a good thermal conductor. This includes mostelectrically insulative materials that would be preferably used for thecasing 2200 to avoid causing a conductive path through contact with thecasing 2200.

It is generally preferable to have the size of the heatsink 2112 assmall as possible while being adequate to prevent the temperature of theLEDs 2110 from becoming excessive, such that the life expectancy of theLED is significantly impacted. Preferably the heatsink will maintain theLEDs 2110 at or below the maximum rated junction temperature of the LEDs2110. This requires dissipation of heat being generated by the LEDs whenin use. A heatsink should be chosen to maintain a temperature below themaximum rated junction temperature of the LEDs 2110 by the temperaturerise of the LED junction above the temperature of the heatsink, or someother selected value depending on the desired working life of the LEDs2110. The temperature rise of the LED junction above the temperature ofthe heatsink may be measured as the amount of power in watts supplied tothe LED multiplied by the LED's thermal resistance, in degrees C. perwatt. Many LED manufacturers provide LED datasheets that mention theirthermal resistance and maximum permissible junction temperature, orother information on which to base the appropriate design of a heatsink.

As an example for the specified components used in the preferredembodiment of the work light 2100, since most white LEDs that have amaximum rated input power near 1.2 watts have a thermal resistance ofapproximately 15-17 degrees C. per watt, the temperature of thesemiconductor chips in the LEDs 2110 will be approximately 18-22 degreesC. hotter than the heatsink 2112. The heatsink 2112 and the slots 2113must dissipate heat adequately for the temperature of the heatsink 2112to be cooler than the maximum rated junction temperature of the LEDs2110 by at least approximately 18-22 degrees C. plus a safety factor ofa few degrees C. when the ambient temperature is the maximum that thework light 2100 is rated to be operated in. Such a heatsink 2112 willtypically have a temperature near or below 75 degrees C. when theambient temperature is 35 degrees C. if the work light is rated foroperation in an ambient temperature as high as 50 degrees C.

Some stock heatsinks are available for which their manufacturers providethermal resistance figures. The junction temperature of an LED would bethe ambient temperature plus the amount of power in watts supplied tothe LED multiplied by the sum of the thermal resistances of the LED andthe heatsink. Where the heatsink is enclosed inside a casing, itseffective thermal resistance can increase and the ambient temperaturefor these calculations may be based on the temperature of the air withinthe casing. Thus, temperature design should be verified for theparticular configuration of each work light.

The shape of the work light 2100 is preferably selected such that theoverall depth of the work light 2100 is minimized to permit use in smallareas such as under the dashboard of an automobile, while allowing theheatsink 2112 to have adequate area for dissipating heat from the LEDs2110. As a result, the work light 2100 as shown has a width greater thanits depth, and the slots 2113 are placed on the rear surface of the worklight 2100. Alternatively, the work light 2100 may have a depth greaterthan its width, in which case the slots 2113 would preferably be placedon the sides of the work light 2100 rather than its rear surface.

It is to be understood that the lights described herein should be ableto withstand prolonged use. Although the lights may sometimes be usedfor short periods of time, often the lights will be used for prolongedperiods of several hours or more while work is being performed. Thetemperature design should take this into account.

Where external casing electrical conductivity is not a concern thenalternative work light embodiments can have a casing, such as casing2200, that is made substantially from a material that is electricallyconductive, for example a metallic casing. Such a casing is likely to bethermally conductive as well and could serve as the heatsink 2112 orpart of the heatsink 2112, in which case the casing continues to enclosethe LEDs and optics and to house the heatsink as the heatsink isintegrated with the casing. This may allow for a reduced heatsink andwork light size, as there may be more effective transfer of heat to theambient air external to the work light. Alternatively, a similar sizecould be chosen with a longer LED life, or possibly the slots 2113 canbe omitted or reduced in size. The material may also be more durablethan many electrically insulative materials.

If external casing electrical conductivity remains a concern then theelectrically conductive casing material can be coated with anelectrically insulative material. The combination of a casingsubstantially made from a material generally considered to be a goodthermal conductor which is also generally considered to be a goodelectrical conductor that is coated in a material that is not consideredto be a good electrical conductor can increase the overall ability ofthe heatsink to transfer heat to the ambient air while limiting thepossibility of creating an electrical conductive path through contactwith the exterior of the casing when the work light in use. The coatingis considered to be part of the casing for the purpose of thisdescription.

The rear casing piece 2102 is non-planar to prevent blocking of theslots 2113 when the work light 2100 is laid down it against the rearcasing piece 2102. Although many other non-planar configurations couldbe used for this purpose, the rear casing piece 2102 is arcuate about alongitudinal axis of the work light 2100 as can best be seen in FIG. 24a.

The slots 2113 are preferably dimensioned so that an operator's skincannot accidentally contact the heatsink 2112. It is possible that suchcontact could result in a burn. Other forms of openings in the casingfor cooling the heatsink could be provided, for example a larger numberof smaller openings in the rear casing piece 2102, for example in areticulated pattern forming a grill, can allow sufficient air movementwhile preventing access to smaller objects than the slots 2113. The sizeand pattern of the openings will need to be configured for theparticular configuration of work light selected, including for examplethe heatsink and LEDs used.

Also mounted to the heatsink 2112 is a circuit board 2114 that may havean LED driver circuit such as a boost converter or one or more currentregulators in order to provide an electrical current through the LEDs2110 reliably of the desired magnitude. Alternatively, droppingresistors may be used in place of circuitry on the circuit board 2114.Further alternatively, the LEDs 2110 may be connected directly to thebatteries 2108 although this is usually not preferred since themagnitude of current flowing through the LEDs may as a result varyexcessively with temperature, battery condition, and variations in theelectrical characteristics of the LEDs 2110. The circuit board 2114 mayhave other circuitry such as a charging circuit for charging anybatteries 2108 or accessory circuitry such as for a paging receiver.

Although the circuit board 2114 is shown as being mounted on theheatsink 2112, it may be mounted anywhere within the work light 2100.

Although the work light 2100 is shown as being powered by batteries, itmay receive power from other sources. The work light 2100 may bedesigned to accept a battery pack 2107 or a similarly shaped plug thatdelivers power from a cord that is connected to a “wall wart” powersupply or to an automotive cigarette lighter plug.

Shown is a switch 2115. The switch may be but is not necessarily of atype that can be used either as a momentary switch when partiallydepressed or as being turned on or off by being fully depressed.

Alternatively, the switch 2115 may be a momentary type and logiccircuitry (not shown) on the circuit board 2114 accepts pulses ofelectricity delivered by a momentary switch 2115 in order to turn on oroff. Further alternatively, circuitry including logic circuitry on thecircuit board 2114 can be switched not only on/off but also through a“cycle” of more than one magnitude of brightness plus an “off state” bydepressing the momentary switch 2115 an appropriate number of times. Forexample, pressing the switch 2115 while the work light 2100 is off canturn it on at full brightness, depressing the switch 2115 a second timereduces the brightness, and pressing the switch 2115 a third time canturn the work light 2100 off.

A switch cap 2118 may be mounted in the rear casing piece 2102 over theswitch 2115. Whether or not a switch cap is used, the switch 2115 may bemounted in a location other than as shown. Alternatively, otherswitching means including remote control means can be used. The switchcap 2118 is preferably made of rubber.

The lens assembly 2111 may be protected from scratching by a transparentlens cover 2116. The lens cover 2116 may be replaceable. Screws 2117 areshown for holding the lens cover 2116 onto the front casing piece 2106.The lens cover 2116 may extend over the insert 2120 to protect it and,possibly, to retain it. Alternatively, as with other embodiments thelens assembly 2111 could itself be a cover for the LEDs 2110.

The work light 2100 has similarities to other embodiments, such as thework light 1200 described in FIG. 13. For example, the lens elements2119 shown in the work light 2100 could work in the same manner as thelens elements 1100 shown in the work light 1200. The lens assembly 2111shown in the work light 2100 is similar to the lens assembly 1201 shownin the work light 1200 except it may lack the walls 1205 of the lensassembly 1201. The work light 2100 is shown as having a battery pack2107 comprising batteries 2108 while the work light 1200 is shown ashaving a battery pack 1207 comprising batteries 1208. The work light2100 has LEDs 2110 while the work light 1200 has LEDs 101. The worklight 2100 has a switch 2115 while the work light 1200 has a switch1212. The circuit board 2114 in the work light 2100 is analogous and maybe similar to the circuit board 1211 in the work light 1200. Some partsthat the work light 2100 could have but which are not shown includewires 1213 shown in the work light 1200 in FIG. 12.

Referring to FIGS. 22, 23 and 24, some of the parts described above forthe work light 2100 shown in FIG. 21 are visible when the light isassembled. The casing 2200 is made up of the front casing piece 2106,rear casing piece 2102 and bottom casing piece 2107 a. The pieces 2106,2102, 2107 a may be held together screws or the like, or by some orretention means such as resoective tabs and grooves on the pieces thatallow for a snap fit. In FIG. 22, a frontal view of the work light 2100shows the front casing piece 2106, the bottom casing piece 2107 a, andthe lens cover 2116. Through the lens cover 2116 the lens assembly 2111including its lens elements 2119 would normally be visible, but havebeen omitted in FIG. 22.

The height H of a preferred embodiment of the work light isapproximately 300 millimeters. The width W of this preferred embodimentis approximately 60 millimeters. The base diameter D2 if this preferredembodiment is approximately 43 millimeters, or sufficiently large tohold the desired batteries while being of a size that is comfortable tohold. As will be evident to those skilled in the art, alternateembodiments with alternate shapes can be made based on the principlesdescribed herein while remaining within the scope of the invention asdefined by some of the claims.

In FIG. 23, a side view of the work light 2100 shows the front casingpiece 2106, the rear casing piece 2102, the bottom casing piece 2107 a,the lens cover 2116, the switch cover 2118, and the additional piece2120 that may have a logo or other information. Also shown are some ofthe ventilation slots 2113.

The depth D1 of the upper portion of the work light 2100 isapproximately 35 millimeters in a preferred embodiment.

In FIG. 24, a rear view shows the rear casing piece 2102, the hook 2101in its retracted position, the hook ball 2104, and the hook clip 2105.Visible features of the rear casing piece 2102 are the ventilation slots2113 and the depression 2103 that the hook fits in when retracted.

Referring to FIG. 25, the work light 2100 is shown with an adapter plug2501 in lieu of the battery pack 2107 shown in FIG. 21. All other parts2101-2106 and 2108-2120 shown in FIG. 21 are shown and any or all ofthese parts may be identical to those in FIG. 21. The work light 2100may have capability of both using a battery pack 2107 as shown in FIG.21 or receiving power from an adapter plug 2501.

The adapter plug 2501 may or may not have the same shape and/or size asthe battery pack 2107.

The adapter plug 2501 is shown including the bottom casing piece 2107 athe way the battery pack 2107 in FIG. 21 does. The bottom casing piece2107 a is shown as a cap that fits over the front casing piece 2106 andthe rear casing piece 2102. Alternatively, the bottom casing piece 2107may be in the form of a plug. Further alternatively, any battery pack2107 or adapter plug 2501 may be in the form of a plug that serves asthe bottom casing piece 2107 a without the bottom casing piece 2107 abeing a distinctly separate part.

The work light may further comprise gaskets or o-rings (not shown)between any of the casing pieces 2102, 2106, and 2107 a forwatertightness or other purposes such as vibration dampening that mayresult in the work light 2100 sounding more sturdy when tapped.

The adapter plug 2501 has a cord 2502 that receives power from anexternal power source (not shown) such as a “wall wart” power supply,line voltage AC, or automotive power. The adapter plug 2501 may havecircuitry within it (not shown) if necessary for the work light 2100 tooperate from the power received through the cord 2502.

The work light 2100 and/or the adapter plug 2501 may have circuitry thatenables the work light 2100 to operate from a wide variety of powersources, such as both line voltage AC and automotive power, both 120volt and 240 volt line voltage AC, or even any AC or DC voltage from 12to 250 volts. Alternatively, the work light 2100 may be supplied withmore than one adapter plug 2501 in order to operate from more than onetype of external power source.

Referring to FIGS. 26, 27 and 28, the hook 2101 is shown in twodifferent positions, with the hook 2101 in an extended position in FIGS.26 and 27 while in FIG. 28 the hook 2101 is retracted into thedepression 2103 in the rear casing piece 2102.

The hook 2101 can take many other positions relative to the casing 2200.The position shown in FIGS. 26 and 27 is a fully extended position forthe work light 2100, where the hook 2102 extends from the top of thelight 2102. A partially extended position is evident in FIG. 34, wherethe hook 2101 extends from the rear of the light 2100. In either ofthese positions the hook 2102 can be rotated about a hook axis 2201(indicated by arrows in FIGS. 21 and 32) through the ball 2104 and thehook 2102.

In the fully extended position the hook axis is perpendicular to the topof the light 2100, while in the partially extended position hook axis2201 is perpendicular to the rear of the light. When in the fullyextended position the beam axis from the light 2100 is generallyperpendicular to the hook axis, whereas in the partially extendedposition the hook axis is generally parallel to the beam of light.

The particular configuration of the hook 2101 is best evident in FIGS.21, 24 and 32. As is evident from the FIGS. and the above description,the ball 2104 fits into a socket 2202. The socket 2202 is enclosed byand partially formed by the hook clip 2105. The hook 2101 has a hookextension portion 2204 and a hook portion 2206. In the work light 2100the hook axis 2201 extends through the hook extension portion 2204 andthe ball 2104. The hook extension portion 2204 extends the hook portion2206 beyond the casing 2200 adjacent the socket 2202 when in the fullyextended and partially extended positions. This allows the hook 2101 torotate about the hook axis 2201 when in these positions while not beingimpeded by the casing 2200. If desired, the casing 2200 can be shapedadjacent the socket 2202 such that the hook 2101 can not be rotatedabout the hook axis 2201 when in one or more positions between thepartially extended position of FIG. 34 and the fully extended positionof FIG. 24. For example, corner 2208 best shown in FIG. 32 can block therotation of the hook about the hook axis 2201 if desired. This can beadvantageous in provided a tactile indication between a partiallyextended and the fully extended position. Alternatively, the hookextension portion 2204 can be of sufficient length for the hook portion2206 to pass the casing 2200 and rotate about the hook axis 2201 in allpositions between the fully extended position and the partially extendedposition of FIG. 33.

Channel 2210 (see in particular FIGS. 21, 24 and 26) extends into thesocket 2202 to permit the hook 2101 to rotate about the ball 2104perpendicular to the hook axis 2201. This allows the hook to movebetween the fully extended and partially extended position. The channel2210 also extends into depression 2103 to allow folding away and storageof the hook extension portion 2204 in the depression 2103.

Hook 2101 can be mounted in the work light 2100 in many alternativeconfigurations that would allow rotation of the hook 2101 about the hookaxis 2201. Such configurations may also include rotation of the hook2101 perpendicular to the hook axis 2201. The hook 2101 does not have tobe mounted on a ball 2103 and socket 2202 in order for this to occur;however, a ball 2103 and socket 2202 is a very effective way of carryingthis out. As an example, the hook 2101 could be alternatively mountedwithout ball 2103 on a double swivel configuration that allows forrotation about the hook axis 2201 and perpendicular to it.

Referring to FIGS. 29 and 30, views are shown of some internal parts ofa work light 2100 a. The work light 2100 a is similar to the work light2100 described above, except that in the work light 2100 a the hook 2100when retracted fits into the heatsink 2112 as shown in FIG. 30. Theshown parts of the work light 2100 a may be similar or identical to thecorresponding parts of the work light 2100, although the heatsink 2112must be deep enough in the work light 2100 a for the hook 2101 toretract into.

Shown are the hook 2101 with its ball 2104, the batteries 2108, the LEDs2110 mounted on the LED board 2109, the heatsink 2112, and the circuitboard 2114.

Referring again to FIG. 32, the work light 2100 has a very compactdesign, in particular in head section 2212 along a dimension parallel tothe beam axis. Internally, casing 2200 sandwiches lens assembly 2111,LEDs 2110 on LED board 2109, and heatsink 2112, such that the componentsare immediately adjacent one another. The LEDs 2110, LED board 2109 andheatsink 2112 are in thermal contact. When viewed in cross-section it isevident that the work light has an elongate profile that is smaller in adimension generally parallel to the beam axis of the light than in anydimension generally perpendicular to the beam axis. In the work light2100 this is true even though the LEDs 2110 and heatsink 2112 occupytogether the dimension generally parallel to the beam axis. In the worklight 2100 this is true even though the casing 2200 may be formed from aelectrically insulative material. In the work light 2100 this is trueeven though the hook 2101 when stored occupies the dimension generallyparallel to the beam axis together with the LEDs 2110 and heatsink 2112.

It is understood that the casing pieces 2102, 2106 and 2107 a combine toform the casing 2200, and that the casing is functionally divided intohead section 2212 and handle section 2214 (see reference numerals onFIGS. 22, 23 and 24).

Referring to FIGS. 32, 33 and 34, the work light 2100 is provided withan accessory mount 3200 (FIG. 32). The accessory mount 3200 receiveswork light accessories, such as a work light mounting device, forexample, stand 3202 (FIG. 33) for the mounting the work light 2100 on agenerally horizontal surface, a mounting bracket 3204 (FIG. 34) formounting the work light 2100 to an external location, such as theunderside of an automotive hood 3206, or an extra hook, not shown.

The accessory mount 3200 is preferably a threaded mount that allows formanually releasable coupling of an accessory. The mount could take otherforms, such as for example a bayonet mount. Where the casing 2200 is arelatively soft material, such as a plastic where threads may wear overtime, the mount 3200 may include an insert, not shown, in the casing2200. The insert could be aof a more durable material, such as brass.The threads of the mount 3200 could then be provided in the brassinsert.

An accessory mounting bracket 3204 could be used in addition to the hook2101 to provide two multiple mounting locations for the work light 2100.Mounting of the work light from multiple mounting locations allows moreflexible positioning of the work light 2100 to direct the beam axis in adesired direction. The mounting bracket 3204 may be rigid to hold thework light in position without additional support means such as the hook2101. The mounting bracket 3204 may be flexibly rigid to allow manualadjustment of the bracket 3204 to adjust the direction of the work light2100.

Referring to FIG. 35, an alternate handle 2214 and battery packimplementation is shown for a battery operated work light, such as worklight 2100. Although it is recognized that the handle and batteryimplementation can be used on other work lights, the implementation willbe described herein with respect to work light 2100. Bottom casing piece2107 a is replaced by a battery contact piece 3500. The piece 3500connects to the front casing piece 2106 and rear casing piece 2102 asdid the base casing piece 2107 a. The piece 3500 has an aperture 3502into the handle cavity 3504.

Battery pack 3506 has a profile that fits through aperture 3502. Thebattery pack 3506 is retained in the handle cavity 3504 byresiliently-loaded (for example, spring loaded) tabs 3508 (one of whichis evident in the FIG.) that fit into slots 3510 (one of which isevident in the FIG.) in the cavity 3504. The tabs 3508 can be retractedby squeezing opposing retention actuators 3512 on an exposed end 3514 ofbattery pack 3506. When inserted the battery pack exposed end 3514 isgenerally flush with handle end 3515.

The battery pack 3506 has contacts 3516 (one of which is evident in theFIG.). The cavity 3504 has corresponding contacts, not shown, for makingelectrical connection from the battery contacts 3516 to componentsinternal to the work light 2100.

Handle end 3515 has charging contacts 3518 for connection to lightcharging contacts 3520 on charging station 3522. As described previouslyfor other embodiments, charging to light 2100 from charging station 3522will occur when battery pack 3506 is inserted in work light 2100.Superimposed on FIG. 36 is an alternate charging position of chargingstation 3522. In this position battery pack 3506 may be inserteddirectly into the charging station 3522 for charging of battery pack3506 without work light 2100. The battery pack is inserted such that thecontacts 3516 engage battery charging contacts 3524 on the chargingstation 3522.

As shown, respective ones of the charging contacts 3520 are connected tothe corresponding respective ones of the charging contacts 3524. Thecontacts 3520 may be separated from the contacts 3524 to allow fordifferent charging features for the light 2100 and standalone batterypack 3506, such as the priority charging discussed previously for otherembodiments. Charging circuitry 3526 such as that described previouslyfor other embodiments is included in the charging station 3522.

To reiterate, only one of the battery pack 3506 or light 2100 containingbattery pack 3506 can be charged at a time in the charging station 3522,notwithstanding that both a battery pack 3506 and a light 2100 are shownin FIG. 36. Other embodiments such as those that have multiple chargingbays may be adapted to the battery pack 3506, handle 2214 and chargingstations 3522 configuration described herein.

Referring to FIGS. 37 and 38, an adaptor plug 3700 has a plug end 3702that is shaped similarly to battery pack 3506. The plug 3700 hascontacts 3704 for making electrical connection to contacts 3518. Thehandle 2214 has threaded inserts 3706 for receiving screws 3708 toretain plug 3700 through holes 3710. Plug 3700 has cord 3712 forconnection to an external power source, not shown. Two-directionalstrain relief 3714 is provided about the cord 3712 where the cord 3712meets the plug 3700.

The adapter plug 3700 may itself be integrated with a mounting device,not shown, for example an articulated arm, such as those commonlyreferred to as a “goose neck”, that terminates in a clamp, magnet orother securing means to allow the work light 2100 to easily converted toan adjustable temporarily fixedly mounted light 2100.

Referring to FIGS. 29, 30 and 30 a, an alternate embodiment of the worklight 2100 is work light 2900. Work light 2900 is quite similar to worklight 2100. Accordingly, only particularly relevant differences will bedescribed herein. Like reference numerals will be used to describe likecomponents. Work light 2900 (reference numeral in FIG. 30 a) has casing2902. Internal components (indicate generally in FIGS. 29 and 30 asreference numeral 2906). Hook 2101 stores in recess 2908 (FIG. 30 a).Contrary to the work light 2100, the hook 2101 in work light 2900 isaligned with the beam axis when stored. In the work light 2100 the hook2101 is perpendicular to the beam axis when stored. As a result thedepth of the light 2900 generally parallel to the beam axis is largerthan that of the work light 2100.

As the hook 2101 stores between fins 2910 (only one fin 2910 isindicated in FIGS. 29, 30 in an exemplary manner) of heatsink 2912, thefins 2910 have room within the casing 2902 for greater depth. Thus theheatsink 2912 can be somewhat narrower or shorter if desired. The hook2101 projects from the casing 2902 when stored to allow a user to accessthe hook 2101. A depression, not shown, could be provided about the hook2101 to allow such access while further increasing the depth of thecasing. This may be preferable as the projection of the hook 2101 tendsto cause the light 2900 to roll when laid on its rear surface 2914.

As can be seen from the shape of the heatsink 2912, but is not asevident in FIG. 30 a, the rear surface 2914 can have a smaller radius ofcurvature than the corresponding surface of the light 2100 whilemaintaining a minimum overall depth with the shown hook 2101 storageconfiguration. The overall depth of the work light 2900 is much closerto its width, while still substantially less than its height.

A removable door 2918 may be provided in casing 2902 to allow forcleaning of the interior of the light in case foreign substances enterthe light 2900, for example through slots 2920. Such a door could beprovided in other embodiments, particularly those with slots through thecasing. The heatsink 2912 and the heatsinks of other embodiments couldbe coated with a non-stick material such as Teflon™ to allow for easycleaning.

Although the work light 2900 has greater depth than the work light 2100it otherwise retains many of the beneficial features of the light 2100.

Any work lights formed from a hard casing may be improved by addingrubber “bumpers” in order to increase survivability of falls andimpacts. The rubber material in any such “bumpers” may be made ofsorbethane rubber which has notable damping properties that may reduce“recoil” effects, and this can reduce bouncing that risks damage fromadditional impacts. Sorbethane rubber or other material that has a highdamping factor may be used in structural parts or added parts to reduceany vibration effects from falls, impacts or other causes.

Any embodiment of the present invention that has batteries may haverechargeable batteries. Any rechargeable batteries comprised inembodiments of the present invention may or may not be removable. Anyembodiment of the present invention having rechargeable batteries orable to be powered by rechargeable batteries may further comprisecharging circuitry or a charger. Any embodiment of the present inventionmay further comprise one or more indicator lamps and/or one or moreother indication devices, such as a battery status indicator, chargingstatus indicator, and/or a temperature indicator. Any embodiment of thepresent invention may have automatic shutdown means for purposes such asprotection from excessive temperature and prevention of excessivedischarge of any batteries. Such automatic shutdown means may includevoltage sensing circuitry, temperature sensing circuitry and/or athermostat or a thermal cutout circuit. Sensing circuitry wouldtypically have to control a switching device such as a relay or atransistor or switching circuitry in order to achieve automatic shutdownof a work light that is experiencing unfavorable conditions such asexcessive temperature or low battery voltage.

Any embodiment of the present invention may or may not be constructed soas to be waterproof, submersible, able to withstand liquids other thanwater, and/or to be explosion proof.

It is noted that in various places throughout this description referencehas been made to components using or formed from rubber. Such componentsmay also employ a thermoplastic elastomer or other similar alternative.

Referring to FIG. 39, a preferred embodiment of the present invention tomake use of low power LEDs 3904 is an LED work light 3900, having a headsection 3901 and a handle section 3902. The LED work light 3900 is shownas having a plastic tube 3903 as a main structural member, which iscommon to both the head section 3901 and the handle section 3902. Theplastic tube 3903 is preferably made of polycarbonate but mayalternatively be made of a different plastic such as acrylic.

The LED work light 3900 has similarities to the LED work light 900described above and shown in FIG. 9. One difference between these isthat the LED work light 3900 is shown as having a transparent structuralplastic tube 3903 serving as its housing. Use of the transparentstructural tube 3903 is mentioned above as an alternative arrangement ofthe LED work light 100 of FIG. 1.

An LED work light can have a housing that is of shape alternative to thetubular LED work light 3900, such as for example any of the otherhousings for work lights described herein, and other housings.

The LED work light 3900 is shown as being powered by a battery 3915,like the LED work light 1200 shown in FIG. 13 and described above.

The LED work light 3900 has at least one LED 3904 and preferably aplurality of LEDs 3904. The LEDs 3904 may be and are shown as low powerLEDs. The LED work light 3900 is shown as having four LEDs 3904,although a different number of LEDs 3904 can be used. LEDs 3904 arepreferably mounted onto an LED board 3906. The LED board 3906 ispreferably a printed circuit board. Any LED board 3906 may have largecopper pads and thermal vias to conduct heat away from LEDs 3904.

Tubular work lights using low power LEDs typically have many LEDs, often30 to 60 LEDs. By employing lenses as described herein, the light 3900can improve the efficiency of illumination such that greater intensityis provided per LED and it is possible to use fewer LEDs if desired. Asthe efficiency of LEDs improves, the LED work light 3900 may utilizeeven fewer LEDs. A combination of the lens and increases in efficiencymay result in embodiments utilizing between 8 and 16 LEDs 3904 toproduce a useful amount of light even if the LEDs 3904 are low powerLEDs.

The LEDs 3904 typically have a dome shaped or circular forward portion.The most common low power LEDs with such a dome shaped forward portionare ones having 5 mm bullet shape, 3 mm bullet shape or 4-lead “highflux” bodies. Such low power LEDs 3904 typically have a maximum ratedcontinuous current of 70 milliamps or less. 3 and 5 mm LEDs 3904typically have a maximum rated continuous current of 30 milliamps,although some have higher ratings such as 35 or 50 milliamps.

Alternatively, the LEDs 3904 may have flat and diffusing forwardsurfaces.

Associated with and forward of each LED 3904 is a convex lens 3905 toform the light from each LED 3904 into a beam. Preferably the beamformed by each lens 3905 is in the form of a projected image of thedome-shaped or diffusing flat forward portion of each LED 3904, althoughit may be found desirable to have this image slightly to moderately outof focus. Alternatively, the beam may be focused in order to have assharp an edge as possible. Beams formed by lenses 3905 are preferablymerging together into a single beam, and preferably with their axesparallel or nearly parallel to each other. The LEDs 3904 and lenses 3905may be arranged to produce beams that converge towards each other, suchas by having the distance between the centers of the LEDs 3904 greaterthan the distance between the centers of the lenses 3905. If thedistance between the centers of the LEDs 3904 is the same as thedistance between the centers of the lenses 3905, then beams formed bythe lenses 3905 would be parallel to each other.

LEDs 3905 preferably are types with their chips substantially rearwardof the edges of their forward surfaces; otherwise, if the lenses 3904are projecting images of the edges of the forward surfaces of the LEDs3904, the lenses 3905 will also be projecting images of the chips of theLEDs 3904, and this will result in bright images of the chips ratherthan the desired images of the forward surfaces of the LEDs 3904.

The lenses 3905 preferably have a focal length equal to or less than 1.4times the diameter of the forward regions of the LEDs 3904. The lenses3905 preferably have sufficient width to collect and process into adesirable beam most of the light produced by the LEDs 3904 The lenses3905 are very thick and placed close to the LEDs 3904. The distancebetween the lenses 3905 and the LEDs 3904 is typically less than thediameter of the LEDs 3904 and may be less than half the diameter of theLEDs 3904 and may be less than half the diameter of the lenses 3905. Thelenses 3905 may have a thickness at least equal to half their width. Thelenses 3905 may have thickness exceeding distance between them and theLEDs 3904. The lenses 3904 may have thickness exceeding twice theirdistance from the LEDs 3904.

The lenses 3905 are preferably aspheric in order to avoid the beamformed by them being blurred by spherical aberration. Alternatively,lenses 3905 with spherical curved surfaces may be tolerated, for exampleto simplify design and fabrication of production tools to produce lenses3905.

The angular width of the beam formed by the lenses 3905 is the same asthe angle between two tangents to the dome shaped forward portion of anLED 3904 that intersect at the principle point of a lens 3905. If thelenses 3905 have a focal length less than 1.4 times the diameter of theregions of the LEDs 3904 being imaged into a circular beam, then thebeam will have a width near or greater than 40 degrees. To increase thebeam width to 90 degrees, the lenses 3905 would have a focal length ofonly half the diameter of the imaged portion of the LEDs 3904.

A benefit of this optical arrangement is redistributing the light fromthe LEDs 3904 into a well-defined beam with minimized waste of lightoutside this beam. The beam formed by the lenses 3905 may be wider ornarrower than the nominal beam angle of the LEDs 3904 or having the sameangular width as the nominal beam angle or “viewing angle” of the LEDs3904. The beam formed by the lenses 3905 can be more intense than thebeam produced by the LEDs 3904 without lenses 3905 even if the beamwidth is unchanged because the percentage of light that is within thedefined beam angle can be increased by use of lenses 3905. The beamformed by the lenses 3905 can also be more uniform in intensity thanthat produced by the LEDs 3904 without lenses 3905.

Lenses 3905 are shown as planoconvex, but may alternatively be biconvexor concavoconvex. Further alternatively lenses 3905 may be fresnellenses. Lenses 3905 may be individual lenses or lens elements in asingle transparent piece of material. Lenses 3905 may be formed in atransparent housing such as the transparent tube 3903.

Lenses 3905 are preferably made of acrylic or polycarbonate.Alternatively lenses 3905 may be made of a different transparentmaterial such as glass. Polycarbonate lenses can be made-thinner thanacrylic ones because polycarbonate has a higher refractive index thanacrylic has. Making a thermoplastic lens thinner improves its ability tobe injection molded.

The LEDS 3904 and lenses 3905 are shown as being arranged to form beamsthat emerge the LED work light 3900 perpendicularly to the axis of thehead section 3901. However, an alternative arrangement may be used toform a beam that emerges from the LED work light 3900 at an angle otherthan perpendicularly to the axis of the head section 3901. The headsection 3901 and the handle section 3902 are shown as having a commonaxis, although alternative arrangements can have the head section andhandle section having axes that are not parallel to each other.

The LED board 3906 is shown as having circuitry 3907 to ensure that thecurrent flowing through the LEDs 3904 is at a proper magnitude. Thecircuitry 3907 may be one or more resistors, linear current regulators,switching current regulators or boost converters. Alternatively, suchcircuitry may be located elsewhere within the LED work light 3900.Further alternatively, it may be found possible to power the LEDs 3904without such circuitry, such as in a case where the LEDs 3904 receivepower from a battery 3915 that has significant internal resistance.

If the LEDs 3904 have chips that have a typical forward voltage drop ofsufficiently less than 3.6-3.75 volts, then each chip in the LEDs 3904can receive power through a resistor from a battery 3915 comprisingthree NiMH cells or one lithium ion or lithium polymer rechargeablecell. If in addition the chips in the LEDs 3904 are connected in seriespairs, then each series pair of LED chips may receive power through aresistor from a battery 3915 comprising six NiMH cells. The battery 3915is shown as comprising six cells, but may comprise a different number ofcells.

It may be considered economically unfavorable to use a switchingregulator or a boost converter in lieu of resistors for circuitry 3907to reduce losses in the circuitry 3907. However, if the voltage drop ofan LED 3904 is too close to the voltage produced by the battery 3915,then resistors may not adequately control the magnitude of currentflowing through the LEDs 3904.

For clarity, electrical connections are not shown. Other embodimentsshown and described above have shown electrical connections that LEDwork lights typically have.

The LED work light 3900 is not shown as having a charging circuit, whichmay or may not be within the LED work light 3900. However, a chargingcircuit may be included, such as in a manner like that described abovefor the LED work light 1200 as shown in FIG. 13. However, a chargingjack 3912 is shown and preferably provided so that the battery 3915 canreceive electrical power for charging.

Also included in the LED work light 3900 is a switch 3911. The switch3911 is preferably a pushbutton switch. The switch 3911 and chargingjack 3912 are shown as being mounted in a base cap 3913. As shown, thebase cap 3913 may be mounted to the plastic tube 3903 with rivets 3914.

The switch 3911 is shown as being mounted in the bottom of the LED worklight 3900. Alternatively it may be mounted in a side surface of the LEDwork light 3900 or the top of the LED work light 3900.

A handle cover 3910 is shown as covering the handle section 3902 of theLED work light 3900. The handle cover preferably also covers much of thebase cap 3915. The handle cover 3910 may be made of rubber. The handlecover 3910 may have an extension 3916 to protect the switch 3911 andcharging jack 3912 from impacts.

The LED work light 3900 is also shown as having a top cap 3908 with ahook 3909. Preferably the hook 3909 can rotate within the top cap 3908.

Preferably the LEDs 3904 produce essentially white light for mostillumination tasks that LED work lights such as the LED work light 3900would be used for. Alternatively a combination of white and colored LEDscan be used in an LED work light 3900 to adjust the overall color or thecolor rendering properties of the light produced by the LED work light3900. For example, one or more red and one or more green LEDs can beused in addition to white LEDs among the LEDs 3904 to achieve either ahigh color rendering index or even exaggerated color renderingcharacteristics. One or more blue LEDs can be added to a combination ofred, green and white LEDs to achieve good or exaggerated color renderingwhile maintaining a high color temperature typical of most white LEDs.Any colored LEDs may or may not have multiple LED chips, diffusing domesor multiple electrical terminals.

The LEDs 3904 can be a combination of white LEDs and colored LEDsselected to address complaints related to use of only white LEDs ofcommon types. The usual complaint is that usage of only common whiteLEDs in an LED work light such as the LED work light 3900 causes thelight produced to be excessively bluish in overall color. Relatedcomplaints of common white LEDs include color rendering issues, whichare mainly red objects being illuminated in a dark and/or dull manner.Often such color rendition complaints include distortion of the colorappearance of purple, brown and orange objects as well as red objects.This can cause one to have difficulty identifying the nominal color of awire with colored insulation, especially if the wire's insulation isdiscolored by age, dirt or other contamination, or by exposure todaylight or harsh chemicals. A cause of such color rendering shortfallsis red spectral content of typical white LEDs being less than that notonly of a more yellowish shade of direct sunlight, but also of similarlybluish daylight.

It has been widely mentioned that a combination of white LEDs and redLEDs can largely solve color rendition problems related to a shortage ofred spectral content. This achieves an effect similar to that of anolder pinkish fluorescent lamp known as “Natural”, wherein the phosphoris a mixture of one similar to that in older formulation “Cool White”and one that specializes in production of red spectral content. The“Natural” fluorescent lamp appears pinkish, and in comparison toincandescent lighting appears purplish. The overall color appearance ofthe “Natural” fluorescent lamp is different from what is usuallyconsidered white to an extent that detracts from its usefulness as ageneral illumination light source. However, the “Natural” fluorescentlamp has been found to be useful in illuminating meat display cases, inorder to make meat appear more red than it appears under the more common“cool white” fluorescent lamp.

It has been noted that a white LED light source can be made less bluishand to a reduced extent pinkish or purplish by combining white LEDs withorange LEDs or yellow LEDs in lieu of red LEDs. However, combining whiteLEDs with orange LEDs achieves little improvement upon a combination ofwhite LEDs and red LEDs in the area of achieving a pleasant overallcolor.

A combination of white LEDs and yellow LEDs of usual amber-yellow ororangish yellow hue can achieve an overall color of the produced lightto be pleasingly less bluish, and only slightly pinkish or purplish incomparison to the color of direct sunlight. Purplishness or pinkishnesscan be completely eliminated if some or all of the yellow LEDs are lessorangish than usual for yellow LEDs.

A combination of white LEDs and yellow LEDs can be improved upon by useof a combination of white LEDs, red LEDs, and green LEDs. The mostobvious improvement in this case is in overall luminous efficacy, sincehigh brightness green LEDs and high brightness red LEDs both largelyhave higher overall luminous efficacy than high brightness yellow LEDshave.

An additional benefit from using green LEDs and red LEDs in lieu ofyellow LEDs in an LED combination of white LEDs and ones that produceyellow light is an improvement in color rendering properties. The degreeto which color rendering properties can be improved by such acombination is generally unexpected, so LED work lights have not beenmade with such a combination due to inaccurately low expectations ofcolor rendering properties of a combination of white, red and greenLEDs. White LEDs typically have a shortfall in spectral content centeredat a much shorter wavelength in the blue-green than the peak emissionwavelength of green LEDs.

One result of color rendering properties of a combination of red, greenand white LEDs is that the overall color of such a combination of red,green and white LEDs can have very high accuracy in rendition ofbrightness of a variety of different red and green objects in comparisonto sunlight. Even bluish green objects, yellowish green objects, andorangish red objects are rendered with essentially the same brightnessas by sunlight as by some combinations of white, red and green LEDs.

Combinations of white LEDs, red LEDs, and green LEDs have been found toachieve such color rendition as measured by percentage of photometricoutput being passed by a deep pure red filter, a bright orangish redfilter, a light bluish green filter, a light yellowish green filter, anda deep green filter.

The bright orangish red filter used for evaluation of LED combinationsis Wratten #25. The deep pure red filter used for such evaluations isWratten #29. The light yellowish green filter used here is Rosco #86,“Pea Green”. The light bluish green filter used here is Rosco #94,“Kelly Green”. The deep green filter used for such evaluations here isRosco #90, “Dark Yellow Green”, which is actually a deep shade of greenthat is hardly yellowish, and achieves a slightly to moderatelyyellowish shade of green output when filtering notably yellowish“incandescent light”. Filters with a Wratten # are sold under thetrademark Wratten of Kodak. Filters with the Rosco numbers are soldunder the trademark Rosco and may obtained from Rosco Canada Ltd. ofMarkham, Ontario, among others.

A combination of red LEDs, green LEDs and white LEDs can be shown tohave extremely good color rendition properties as evaluated using theabove filters if:

the red LEDs are typical InGaAlP ones with dominant wavelength close to625 nm and accordingly having CIE 1931 chromaticity coordinates ofx=0.7, y=0.3,

the green LEDs are InGaAlP ones having CIE 1931 chromaticity coordinatesof x=0.17, y=0.7, such as InGaAlP ones such as usual color rank G onesby Nichia, and

the white LEDs are ones with usual overall color and usual colorrendering properties as exemplified by ones of typical overall color andcolor rendering properties of ones by Nichia.

A usual red InGaAlP LED has 84% of its photometric output able to passthrough a Wratten #25 filter, 63% of its photometric output able to passthrough a Wratten #29 filter, 17.5% of its output able to pass through aRosco #86 filter, 0.1% of its output able to pass through a Rosco #90filter, and 0.4% of its output able to pass through a Rosco #94 filter.

A usual green InGaAlN green LED as exemplified by Nichia G color rankones has 0.35% of its photometric output ale to pass through a Wratten#25 filter, 0.15% of its photometric output able to pass through aWratten #29 filter, 63% of its output able to pass through a Rosco #86filter, 18.3% of its output able to pass through a Rosco #90 filter, and37.5% of its output able to pass through a Rosco #94 filter.

A usual white LED as exemplified by many to most white low power LEDsmanufactured by Nichia has been found to typically have 1931 CIEchromaticity coordinates of approximately x=0.33, y=0.32. This isslightly more reddish than Nichia's published 1931 CIE chromaticitycoordinates of x=0.31, y=0.32 for most of their low power white LEDs ingeneral. A light source that has 1931 CIE chromaticity coordinates ofx=0.31, y=0.32 has overall color close to that of a bluish shade ofdaylight that has a color temperature of 6500 K. Many to most Nichia lowpower white LEDs have a color appearance that is pinkish in comparisonto daylight that achieves a color temperature of 6500 K.

A white LED as exemplified by typical Nichia low power ones has 11.5% ofits photometric output ale to pass through a Wratten #25 filter, 4.3% ofits photometric output able to pass through a Wratten #29 filter, 50% ofits output able to pass through a Rosco #86 filter, 9.1% of its outputable to pass through a Rosco #90 filter, and 19.5% of its output able topass through a Rosco #94 filter.

An LED work light such as the LED work light 3900 can be shown by meansof calculation methods known to those skilled in calorimetriccalculations to achieve a whiter-sunlight overall color with colortemperature of 4850 Kelvin if its LEDs 3904 comprise a combination ofone or more above red LEDs, one or more above green LEDs, and one ormore above white LEDs such that 7 percent of the photometric content inthe emitted light is from the one or more above red LEDs, 17.5 percentof the photometric output is from the one or more of the above greenLEDs, and the remaining 75.5% of the photometric output is from anynumber of the above white LEDs. It is noted that in this example thegreen LEDs contribute more than twice as much photometric output as thered LEDs do.

To determine theoretically the overall 1931 CIE chromaticity of acombination of light sources whose 1931 CIE chromaticities andquantitative photometric outputs are known, calculations such as thefollowing can be used. The calculations below have anoversimplification, by assuming that photometric properties of variouswavelengths of light follow the 1924 photopic function, which the CIE1931 Y color matching function is arbitrarily set equal to. The photopicfunction of wavelength was redefined in 1988. This causes only small toinsignificant errors when a combination of light sources being evaluatedhas only a small percentage of its photometric content at wavelengthsless than 455 nm.

First, X, Y and Z chromaticity contributions of individual light sourcesmust be determined. The Y contributions of each source can be defined tobe their photometric outputs, whether in terms of luminous intensity orluminous flux, or percentage or fraction of either luminous intensity orluminous flux. The X contribution of each source is its Y contributiontimes its x 1931 CIE chromaticity coordinate divided by its ycoordinate. The Z contribution of each source is similarly Ycontribution times its z chromaticity coordinate divided by its ychromaticity coordinate. The z 1931 CIE chromaticity coordinate isusually not stated and is equal to 1 minus the sum of the x any ycoordinates.

Using as an example the above combination of LEDs where:

7% of the photometric output is from red LEDs having chromaticitycoordinates of x 0.7 y 0.3 z 0,

17.5% of the photometric output is from green LEDs having chromaticitycoordinates of x 0.17 y 0.7 z 0.13, and

75.5% of the photometric output is from white LEDs having chromaticitycoordinates of x 0.33 y 0.32 z 0.35,

The Y chromaticity contributions of each of these LEDs are:

0.07 for the red LEDs, 0.175 for the green LEDs, and 75.5 for the whiteLEDs, using percentages of total photometric output that is from eachcolor of LEDs.

The X chromaticity contributions are:

0.07*0.7/0.3 or 0.1633 for the red LEDs,

0.175*0.171/7 or 0.0425 for the green LEDs, and

0.755*0.33/0.32 or 0.7786 for the white LEDs.

The Z chromaticity contributions are:

0.07*0/0.3 or 0 for the red LEDs,

0.175*0.13/0.7 or 0.0325 for the green LEDs,

and 0.755*0.35/0.32 or 0.826 for the white LEDs.

The next step in determining theoretically the overall chromaticity isto add up the X contributions, the Y contributions, and the Zcontributions.

The total X contribution in this example is 0.1633+0.0425+0.7786, or0.9844.

The total Y chromaticity contribution in this example is 1, since theindividual contributions are the same as their fraction of the totalphotometric content of the combination of LEDs.

The total Z chromaticity contribution in this example, determined in amanner like that of the X contribution, is 0.8585.

The x and y chromaticity coordinates are respectively the X and Y totalchromaticity contributions divided by the sum of all three chromaticitycontributions. In this example, the overall x coordinate is0.9844/(0.9844+1+0.8585), or 0.346. The y chromaticity coordinate issimilarly 1/(0.9844+1+0.8585), or 0.352. This is very close to thechromaticity of a 4950 Kelvin blackbody radiator.

Percentage of light from the above LED combination passing through eachof the five above filters respectively is equal to 1/100 of the sum ofthe products of:

percentage of the total photometric content of an LED combination thatis from each color LED, and

percentage of photometric content from each color LED that is able topass through the respective filter.

The percentage of photometric output from such a combination of LEDsthat can be used as the LEDs 3904 has percentage of its output asmeasured with a Lutron LX-101A light meter able to pass through theabove 2 different red filters and the 3 above different green filtersbeing:

14.6% for the Wratten #25 orangish red filter,

7.7% for the Wratten #29 deep red filter,

50% for the Rosco #86 light yellowish green filter,

10.1% for the Rosco #90 deep green filter, and

21.3% for the Rosco #94 bluish green filter.

In comparison, direct sunlight obtained with the sun 25-28 degrees abovethe horizon and having a color temperature estimated to be 4100-4300 Khas as averaged among multiple measurements the following percentages ofphotometric content able to pass through the same filters according tothe same light meter:

14.5% of the sunlight's photometric content passes through the Wratten#25 filter,

7% of the sunlight's photometric content passes through the Wratten #29filter,

49% of the sunlight's photometric content passes through the Rosco #86filter,

10.1% of the sunlight's photometric content passes through the Rosco #90filter, and

21.5% of the sunlight's photometric content passes through the Rosco #94filter.

Such results indicate that a combination of red LEDs, green LEDs andwhite LEDs is particularly able to achieve color rendering propertieslike those of sunlight.

The overall color and color rendering properties of an LED lamp such asthe LED work light 3900 can be improved to a lesser but significantextent in comparison to usage of only white LEDs if it has a combinationof red, green and white LEDs where the percentage of photometric contentthat is from the red LEDs is as little as half the 7% that can achievesunlight-like color rendering properties. The percentage of photometriccontent from green LEDs typically has to exceed that of the red LEDs,often by a factor of at least 1.5, in order for the combination of thered LEDs and green LEDs to be combined to make the overall color of theLED combination less bluish without being more pinkish. Additional greenLEDs may be needed in such an LED combination to offset the purplishnessof many white LEDs, and these additional green LEDs can have photometricoutput as much as 6 percent of that of the white LEDs.

If an LED work light 3900 is to be made with the above-described red,green and white LEDs for use as the LEDs 3904 and with photometriccontent from red LEDs being 3.5% of the total photometric content inorder to halfway correct the red insufficiency of the white LEDs, thenthe LED work light 3900 would have 12% of its photometric output fromthe green LEDs among the LEDs 3904 and a color temperature close to 5400Kelvin, and without a greenish appearance or significantly excessivelybright rendition of illuminated green objects. It is noted that a whiteLED light can be achieved with somewhat usefully improved colorrendering properties by using a combination of red LEDs, green LEDs andwhite LEDs where the green LEDs have over triple the photometriccontribution of the red LEDs and over 10% of the total photometricoutput is from the green LEDs. In this example, the green LEDscontribute more than three times as much photometric output as the redLEDs do.

Use of much more photometric output from green LEDs than from red LEDsin a combination of red, green and white LEDs is typically unexpected toachieve a good result, since color rendition complaints of white lightsources tend to be ones of insufficiency in red illumination propertiesand not insufficiency of green illumination properties. Some colorrendition complaints of non-incandescent artificial white light sourcesare excessive greenishness, and such complaints significantly outnumberones of insufficient green illumination tendencies. However, such acombination of red LEDs, green LEDs and white LEDs with close to or evenmore than twice as much photometric output from green LEDs as from redLEDs if used as the LEDs 3904 in the LED work light 3900 does achieveoverall color and color rendering properties typical of direct sunlight.

Such an LED combination is typically expected to have excessivegreenishness or excessively bright rendition of illuminated greenobjects until it is actually tested.

Furthermore, combinations of red LEDs, green LEDs, and white LEDs thatachieve more than 7% of photometric content being from red LEDs and morethan 17.5% of photometric content from green LEDs can be found to beuseful to an extent that is typically unexpected until such combinationsare actually tested or analyzed. For example, a complaint of lightingwith a sunlight-like light that has a correlated color temperature nearor above 4000 Kelvin is from illuminated red objects appearing darkerthan expected if the illumination intensity is much less than theapproximately 1000-2000 lux typical of office lighting, classroomlighting and bright retail lighting. Illumination levels in homelighting and in illumination of areas illuminated by work lights such asthe LED work light 3900 are often less than 200 lux, and it is knownthat red objects can appear darker when the illumination level is closeto this low or less.

One solution to address the problem of red objects appearing dark attypical illumination levels at homes and work areas illuminated by worklights is to use incandescent lamps, since incandescent lamps are richin red spectral content. Red illumination properties of incandescentlamps as well as other light sources can be measured in part bypercentage of photometric content from a light source in question thatis able to pass through Wratten 25 and 29 red filters.

A 60 watt “soft white” incandescent lamp having color temperature closeto or slightly less than 2800 Kelvin has 22.6% of its photometriccontent able to pass through a Wratten #25 filter according to a lightmeter described above, and 12.8% of its photometric content able to passthrough a Wratten #29 filter according to the same light meter.

Another remedy to darker illumination of red objects at lowerillumination levels by light with sunlight-like illumination propertiesis by usage of a combination of red LEDs, green LEDs and white LEDswherein more than 7% of the photometric output is from the red LEDs. Forexample, an LED work light such as the LED work light 3900 can have 15%of its photometric output from red LEDs described above, 27% of itsphotometric output from green LEDs described above, and 58% of itsphotometric output from white LEDs as described above in order to haveoverall color of emitted light essentially matching that of a 4100Kelvin blackbody radiator. This is a shade of white that is widely usedas a standard for fluorescent lamps and metal halide lamps toapproximate, and is a color that direct sunlight achieves if it isslightly more yellow than that of typical midlatitude high-noon directsunlight.

If an LED work light such as the LED work light 3900 has its LEDs 3904being the immediately above combination of one or more red LEDs, one ormore green LEDs and one or more white LEDs so that it produces lighthaving a color temperature of 4100 Kelvin by having 15% of itsphotometric output from one or more red LEDs and 27% of its photometricoutput from one or more green LEDs and the remaining 58% of itsphotometric output from one or more white LEDs, then it can be shownthat red objects will generally be illuminated to a moderate extent morebrightly than by same illumination level and same overall color ofdirect sunlight, and that green objects will generally be illuminatedthe same as if they are illuminated by same intensity and overall colorof direct sunlight.

Such an LED combination has the following percentages of its photometricoutput able to pass, through the five above-mentioned red and greenfilters:

19.4% passing through the Wratten #25 orangish red filter,

12% passing through the Wratten #29 deep red filter,

48.6% passing through the Rosco #86 light yellow-green filter,

0.1% passing through the Rosco #90 deep green filter, and

21.4% passing through the Rosco #94 bluish green filter.

In comparison to sunlight, such an LED combination achieves increasedred illumination and essentially unchanged green illumination. This isachieved by adding almost twice, specifically 1.8 times as much lightfrom green LEDs as from red LEDs to the light from white LEDs, and suchresults are generally unexpected until such an LED combination isactually tested.

Such a combination of red LEDs, green LEDs and white LEDs can be foundto be useful by achieving illumination having a desirable overall colorlike that typically achieved from fluorescent lamps while not renderinggreen objects more brightly than they would be illuminated by the sameillumination level of sunlight of same overall color, while illuminatingred objects moderately more brightly than is achieved by same level ofillumination by sunlight of same overall color.

Usefulness of such a 4100 Kelvin version of the LED work light 3900 willbe largely maintained if the correlated color temperature is even lowerthan 4100 Kelvin since a lower correlated color temperature would beachieved with a higher percentage of the LEDs 3904 being red LEDs.

A correlated color temperature of 3840 K, close to 3800 K, can beachieved by a combination of LEDs 3904 having 18.5% of its photometriccontent from the above red LEDs, 31.5% of the photometric content fromthe above green LEDs, and 50% of the photometric content from the abovewhite LEDs. This is approximately the color of carbon arcs and istypically considered a pleasing, slightly warmish white. This has thephotometric output from the green LEDs being 1.7 times that of the redLEDs. The light from such a combination of LEDs 3904 has 21.4% of itsphotometric content able to pass through a Wratten #25 filter, and 13.8%of its photometric content being able to pass through a Wratten #29filter according to the above light meter. These figures are close tothose for the above incandescent lamp.

It is noted that usefulness is expected with photometric content of thewhite LEDs being as low as 50% of the total photometric output of allLEDs, and with photometric content of the white LEDs being as great as85.5% of the total photometric output of all LEDs. However, redbrightness rendition is more likely to be enhanced in comparison tosunlight if the white LEDs contribute close to or less than 75.5% of thetotal photometric output as shown above.

The usefulness of such combinations of white, red and green LEDs is notlimited to LED work lights such as the LED work light 3900. Such LEDcombinations can also be found useful in other lighting applications,such as desk lamps and accent lights. Such LED combinations may be usedin ambient lighting when the cost of LEDs decreases sufficiently to makeLED ambient lighting commercially practical.

In such above LED combinations to be used as the LEDs 3904, the red LEDsare InGaAlP ones with dominant wavelength of 625 nm and a typicaltolerance range of 620 to 635 nm, and the green LEDs are InGaN ones withdominant wavelength of 525 nm and a typical tolerance range of 515 to535 nm. Other red LEDs or reddish LEDs such as orange LEDs or use ofboth red and orange LEDs, and also other green LEDs may be found usefulto combine with white LEDs to achieve a good overall color and goodcolor rendering properties of an LED work light 3900.

The LED work light 3900 may have LEDs without lenses in addition to theLEDs 3904 that are associated with lenses 3905. Such additional LEDs maybe indicator lamps, such as to indicate the charge status of the battery3915. Such indicator lamps may be a red LED to indicate that electricalpower is being supplied to charge the battery 3915, a green LED toindicate that charging of the battery 3915 is complete, and a yellow LEDto indicate that the battery 3915 should be recharged. Such indicatorlamp LEDs would preferably be controlled by the charging circuit orcircuitry associated with the charging circuit (not shown in the LEDwork light 3900).

Referring to FIG. 40, an LED work light 3900 a is essentially the LEDwork light 3900 with a diffuser 4001 being added immediately forward ofthe LEDs 3904. The LEDs 3904 produce bright illuminated spots on thediffuser 4001. The lenses 3905 produce beams of light merging into asingle beam and in the form of coinciding projected images of the brightilluminated spots on the diffuser 4001. The lenses 3905 would typicallyaccordingly be located with their focal points at or near the diffuser4001.

The lenses 3905 may be located to have their focal points displacedslightly from the diffuser 4001 in order to avoid forming a beam thatincludes a focused image of small irregularities in the diffuser 4001,such as texture details in the diffuser 4001 or particles of dust ordirt. If the focal points of the lenses 3905 are displaced from thediffuser 4001, then it is typically preferable to have this done byhaving the lenses displaced closer to rather than farther from thediffuser 4001. Placing the lenses 3905 closer to the diffuser 4001increases the percentage of light from the LEDs 3904 that is collectedby the lenses 3905.

The diffuser 4001 can allow the beam of light formed by each of thelenses 3905 to be more uniform than it would be if the diffuser 4001 isnot used. The diffuser 4001 can also be used to achieve beams that haveslightly blurred edges. These effects can assist in uniform mixing ofthe light if beams formed from different color LEDs 3904 are mergedtogether into a single beam.

As an alternative to using the diffuser 4001, the LEDs 3904 in the LEDwork light 3900 of FIG. 39 may have diffusion built in, such as bymaking their bodies translucent rather than transparent or by texturingtheir forward surfaces. Such diffusing LEDs may have either flat orcurved forward surfaces.

Referring to FIG. 41, a lens 4106 is shown. The lenses 3904 describedabove may be shaped like the lens 4106, since the lens 4106 projects animage from a light source located close to the rear surface of the lens4106, and with the light source having a wide beam angle. The LEDs 3905described above will typically work well with lenses 3904 shaped likethe lens 4106 if they are wide beam LEDs such as “high flux” ones,diffused ones or ones having a flat forward surface.

The lens 4106, if used as lenses 3904 in an LED work light 3900 or in analternative LED work light 3900 a described above, preferably has adiameter not much greater than that of its corresponding LED 3904 inorder for each LED 3904 to have forward of it an associated lens 4106 inan array of LEDs 3904 spaced close together. When a lens 4106 is thatsmall, its focal length will be similarly small, typically 0.707 to 1.4times the diameter of its associated LED 3904.

The concave rear surface 4106 a of the lens 4106 may follow a curvedefined by a polynomial function of a radius from axis 4106 c of thelens 4106. The concave rear surface 4106 a may be spherical, ellipsoidalor paraboloidal. The concave rear surface 4106 a of the lens 4106 mayhave a shape that is a combination of an ellipsoid or spheroid and ashape generated by a polynomial function.

The front surface 4106 b of the lens 4106 is typically aspheric. Theshape of the front surface 4106 b of the lens 4106 may be ellipsoidal,of a shape generated by a polynomial function of radius from the axis4106 c of the lens 4106, or a combination of a polynomial function shapeand an ellipsoid or sphere.

The lens 4106 is mounted close to the LED 4102 and has a very highlyconvex front surface 4106 b in order to collimate light collected by thelens 4106 from an LED 4102 having a wide radiation pattern. Typicallythe thickness of the lens 4106 between the front surface 4106 b and therear surface 4106 a along the axis 4106 c exceeds the distance betweenthe lens 4106 and the LED 4102 along the axis 4106 c in order tocollimate most of the light from an LED 4102 having a nominal radiationpattern width of 4100 degrees or more. The distance between the LED 4102and the lens 4106 may be half the thickness of the lens 4106 or less.

The lens 4106 may be cast from a castable polymer such as acrylic,castable polycarbonate, or epoxy. Alternatively, the lens 4106 may bemachined from a suitable material such as acrylic or thermoplasticpolycarbonate and polished after machining. If the lens 4106 ismachined, it may be machined by means of a lathe such as a CNC lathe.Further alternatively, the lens 4106 may be injection molded if shapedistortions that occur during cooling can be avoided or fixed. The lens4106 may alternatively be made of a non-polymer material such as glassor quartz, or made of a polymer by means other than casting, machining,or injection molding. Other methods of manufacturing a lens 4106 will beevident to those skilled in the art based on their common generalknowledge and the principles described herein.

With continuing reference to FIG. 41, light rays 113 produced by the LED4102 pass through the lens 4106. The lens 4106 has a convex frontsurface 4106 b and a rear surface 4106 a. The rear surface 4106 a ispreferably concave. Either or both surfaces 4106 a, 4106 b may beaspheric. Preferably the front surface 4106 b is approximatelyellipsoidal since a lens 4106 with an ellipsoidal front surface 4106 bworks reasonably well according to ray tracing software. A sphericalfront surface would have its outer region excessively parallel to rayshitting it, resulting in excessive reflection loss of these rays. Inaddition, any of such rays hitting the outer region of a spherical frontsurface and not completely lost by total internal reflection wouldemerge from the front surface converging towards the axis of the lens4106.

Referring to FIGS. 42-46, details of possible relationships between thelenses and LEDs in LED spotlights wherein the lenses produce beams byprojecting images of the edges of the forward regions of theirassociated LEDs will now be discussed.

Referring to FIG. 42, a convergent lens 4201 can form an image 4203 ofan object 4205. If the object 4205 is at the focal point 4207 of thelens 4201 (on one side of the lens), or at a distance (OD) from the lens4201 equal to the focal length (F) of the lens 4201; then an image 4203is formed at the other side of the lens 4201 at infinite distance (ID)from the lens 4201.

There is a relationship among object 4203 distance (from the lens 4201),image distance (ID) (from the lens 4201), and focal length (F) of thelens 4201:

$\frac{1}{{object}\mspace{14mu} {distance}} = {\frac{1}{{image}\mspace{14mu} {distance}} = \frac{1}{{focal}\mspace{14mu} {length}}}$

Each lens of a multi-lens multi-LED lamp, embodiments of which aredescribed herein, makes good use of only the one LED with which it isassociated. Each LED-lens combination concentrates the beam from theLED. These beams operate optically independent of each other but areaimed onto a common target and thus “superimposed”.

Referring to FIG. 43 ray paths involved in formation of an image 4300 ofthe front surface 4301 of an LED 4303 are shown. The LED 4303 isseparated from lens 4305 by a distance slightly greater than the focallength of the lens 4305 and the image 4300 is formed at some distinctdistance from the lens 4305. The image 4300 of the front surface 4301 ofthe LED 4303 is an attractive bright circle, assuming that all portionsof the front surface 4301 of the LED 4303 are passing rays utilized bythe lens 4305.

Referring to FIG. 44, rays from the edges of the LED 4303 are shownpassing through the center of the lens 4305 to the edges of the image4300, to illustrate the beam angle as a function of LED diameter (LD)and the distance (OD) from the LED 4303 to the lens 4305. Theoreticallyexactly, the tangent of half the beam angular diameter is equal to theratio of LED radius (½ LD) to its distance (OD) from the lens 4305. As auseful approximation, the beam diameter in radians will usually be theratio of LED diameter (LD) to the distance (OD) from the LED 4303 to thelens 4305. Multiplying this figure by 57.3 gives an approximate beamangular diameter in degrees.

Referring to FIG. 45, shifting the LED 4303 slightly to one side (S) ofthe axis of the lens 4305 causes the resulting beam to form at a slightangle from the axis of the lens 4305.

Referring to FIG. 46, two LED-lens combinations 4305 a/4303 a, 4305b/4303 b with LEDs offset from the axes of their associated lensesproduce two beams A, B that coincide at a specific distance (CD) fromthe lenses 4305. Not shown in FIG. 46 are rays explaining how the beamsare best-defined at the same distance. However, design of a lamp such asthe LED work light 3900 having multiple “independent units” eachconsisting of an LED 4303 and a lens 4305 would preferably have thebeams best-defined (focused images of the front surfaces of the LEDs) atthe same distance at which their centerlines intersect.

Although it is not strictly necessary to have a focused image, itminimizes light wasted into a less illuminated “blur zone”. Anotheradvantage of a beam with sharp edges is that a sharp beam edge makes iteasier to determine whether or not an area being viewed is beingilluminated by the beam.

The above explains how a multi-lens multi-LED lamp produces a beam whichis attractive and impressive at a specific distance from the lenses. Itis desirable to have as wide a range of useful “working distance” aspossible.

Generally, a shorter lens focal length compared to the “typical workingdistance” or “design working distance” results in the beams beingwell-defined over a wider range of distances. In addition, a shorterfocal length results in a wider beam. The “usual size” of LED is 5 mm(often known in the USA as “T1-3/4”), with the next-most-common sizebeing 3 mm (often known in the USA as “T1”).

One more consideration is making the lines passing through the center ofthe LEDs and the “principal point” or effective optical center of itsassociated lens to have the least possible angle of convergence. Thismakes the beams largely coincide with each other over a larger range ofdistances. One way to make the beam axes have a reduced angle ofconvergence is to use smaller diameter lenses.

However, the lenses must be large enough to catch most of the outputbeams of the LEDs. If the lenses have a shorter focal length, then theyare placed closer to their associated LEDs, and this allows smallerlenses to collect most of the light from their associated LEDs.

One more consideration is that the angular diameter of each beam exitinga lens should exceed the angle between axes of the beams. Achieving thisassures that all individual beams merge into each other at leastpartially for all distances from about half the “design target distance”to infinite distance. This is easily achieved when each beam has a widewidth of at least 40 degrees.

The angle between beam centers, in degrees, is approximately 57.3 timesthe ratio of lens spacing (between centers of lenses in opposite cornersof the lens assembly) to design target distance from the lens.

As noted above with respect to FIG. 46, usual convex lenses 4305 in ausual configuration require the LEDs 4303 to be offset vertically andhorizontally from the axes of the lenses 4305. A disadvantage of this isthat the LEDs 4303 must be slightly tilted to be aimed at the centers ofthe lenses 4305 or the lenses 4305 must be large enough to capture“off-center” LED beams.

If the lenses 4305 have a “prismatic effect” of bending a ray passingthrough the center of the area of the lens, then the LED 4303 can bemounted directly behind the lens 4305 with the LED 4303 and lens 4305having a common axis parallel to that of an inspection lamp. The lens4305 would then form a beam which exits the lens 4305 at an angle fromthe axis of the lens 4305.

A lens specification in an LED lamp having a lens forward of each LEDsuch as the LED work light 3900 can be determined as follows:

The distance between the principal point of the lens and its associatedLED should be the diameter of the portion of the associated LED toproject an image of to form a beam, divided by twice the tangent of halfthe desired angular width of the beam. Since the characteristics of thebeam will normally be considered at distances from the lens that arevery great compared to the distance between the LED and the principalpoint of the lens, the lens would typically have a focal length nearlyequal to the distance between the LED and the principal point of thelens.

The lens should be barely wide enough to capture the beam produced bythe LED. Multiply the LED's distance from the rear surface of the lensby twice the tangent of half the beam angle of the LED, and add to thisthe LED's diameter. Alternatively, determine experimentally how wide alens is required to capture the LED's beam at the distance from the LEDthat the lens is to be located at.

LEDs that work well in the LED work light 3900 may be 5 mm diameterdiffused LEDs. To form a beam that is 60 degrees wide for example, theLED need be only 4.33 mm from the principal point of the lens, and thelens would have a focal length close to 4.33 mm.

Preferably, each LED is located directly behind the center of itsassociated lens. Since the LEDs are usually close to each other andtheir associated lenses are close to each other and the beams formed bythese lenses are wide, the beams typically merge together into a singlebeam. The combined beam typically has a width hardly greater than thewidth of each of its component individual beams at distances near orover 2 feet from the lenses.

Alternatively, it may be desired to have the individual beams convergetowards each other to be fully coinciding with and superimposed uponeach other at a specific distance or target distance forward of thelenses. In that case, the distance between the centers of adjacent LEDswould exceed the distance between the centers of their associatedadjacent lenses by the distance between each LED and the principle pointof its associated lens times the ratio of distance between centers ofadjacent lenses to the target distance. Since the focal length of thelenses is typically very small compared to a typical target distance,the distance between each LED and the principle point of its associatedlens will be very close to the focal length of the lens.

For example, if the beams are intended to be fully coinciding with eachother 500 mm from the lenses and the center of each lens is 10 mm fromthe center of a neighboring lens, and each lens has its principal point4.33 mm from its associated LED, the distance between the axis of an LEDand the axis of a correspondingly neighboring LED would be 10 mm+4.33mm*(10 mm/500 mm) or 10.09 mm.

a) In some embodiments, ordinary convex lenses (with optical centercoinciding with the center of the area of each lens) are used and thecenters of the LEDs are spaced slightly further apart than the centersof the lenses such that rays from the lens centers pass through the lenscenters unbent and converge upon the center of the target area. The LEDswould be angled to aim them at the lens centers.

b) A variation of such embodiments would have the lens centers closertogether than the LED centers, but the LEDs are not aimed at the lenscenters. The lenses would then need to be wide enough to capture thebeams from the LEDs. This means that the lens radius needs to exceed thebeam radius by the offset between the LED's axis and the axis of thelens in order for the lens to capture the beam.

c) Lenses with optical center or principal point offset to one side fromthe midpoint of the lens can be used. Each LED can be directly behindthe midpoint of the lens, but the optical center (center of curvature ofcurved surfaces) is offset from the midpoint of the lens (or lenselement) so that a ray passing through the midpoint of the lens is bent.

Referring to FIGS. 47 and 48, the relationship of focal length of lens4701 and diameter of LED 4702 are illustrated along with the size of theimage 4703 that they produce. Some applications will require that thesame image size must be produced at a distance that is twice that of thefirst design. This can be accomplished by using a lens 4801 whose focallength is twice that of lens 4701 with LED 4702 and doubling the spacingbetween the lens 4801 and LED 4702. The resultant spot of light or image4803 will then be both smaller and brighter than the results obtained atthis increased distance from LED 4702 and lens 4701.

It will be understood by those skilled in the art that this descriptionis made with reference to the preferred embodiment and that it ispossible to make other embodiments employing the principles of theinvention which fall within its spirit and scope as defined by thefollowing claims. In particular and without limiting the above, personsskilled in the art will recognize that various features and functions ofthe different embodiments described herein will be useful in otherembodiments, and that such features and functions may be used in suchother embodiments to create new embodiments employing the principles ofthe invention.

1. An LED work light, comprising: a handle section and a head section,and a plurality of LEDs mounted in the head section, and means for theplurality of LEDs to receive electrical power, wherein: each LED withinthe plurality of LEDs is associated with a lens that is located forwardof its associated LED, the lens associated with each LED in theplurality of LEDs forms a beam by projecting an image of the forwardregion of its associated LED, and wherein all of the said lensesassociated with LEDs in the plurality of LEDs form beams that mergetogether to form a useful combined beam substantially between 40 and 90degrees.
 2. The LED work light of claim 1, wherein the lenses have focallength not greater than 1.4 times the width of the forward regions oftheir associated LEDs.
 3. The LED work light of claim 2, wherein thelenses have thickness at least half their diameters.
 4. The LED worklight of claim 2, wherein each lens has thickness greater than thedistance between each lens and its associated LED.
 5. The LED work lightof claim 4, wherein each lens has thickness at least twice the distancebetween each lens and its associated LED.
 6. The LED work light of claim2, wherein each lens has a thickness equal to or greater than half thediameter of each lens.
 7. The LED work light of claim 1, wherein thelenses are used to produce a beam having a higher percentage of thetotal light output being within the beam than would be the case if thelenses are omitted.
 8. The LED work light of claim 7, wherein the lensesproject a beam of light that is not narrower than that produced by theLEDs.
 9. An LED lamp, comprising: a plurality of LEDs to provide lightthat is useful for illumination purposes, wherein the plurality of LEDsthat produces light useful for includes: one or more red LEDs, one ormore green LEDs, one or more white LEDs, and wherein the plurality ofLEDs produces light that is mixed to produce a combined light outputthat has color approximating that of a blackbody radiator and having acorrelated color temperature of 3,800 to 5,400 Kelvin.
 10. The LED lamplight of claim 9, wherein the LED lamp is an LED work light having ahead section and a handle section.
 11. The LED lamp of claim 9, whereinthe photometric output from the one or more green LEDs exceeds thephotometric output of the one or more red LEDs.
 12. The LED lamp ofclaim 9, with the ratio of the photometric output from the one or moregreen LEDs to the photometric output from the one or more red LEDsexceeding 1.5.
 13. The LED lamp of claim 12, with the photometric outputfrom the one or more green LEDs being essentially approximating 1.8times that from the red LEDs.
 14. The LED lamp of claim 12, with thephotometric content from the one or more green LEDs being at least twicethat of the red LEDs.
 15. The LED lamp of claim 14, with the photometriccontent from the one or more green LEDs being at least 3 times that fromthe one or more red LEDs.
 16. The LED lamp of claim 11 where the redLEDs contribute 3.5 to 18.5 percent of the total photometric output. 17.The LED lamp light of claim 11, wherein the white LEDs contribute atleast half of the photometric output.
 18. The LED lamp of claim 17,wherein the LED lamp is a work light having a head section and a handlesection.
 19. An LED work light, comprising: a handle section and a headsection, and a plurality of LEDs mounted in the head section, and meansfor the plurality of LEDs to receive electrical power, wherein: each LEDwithin the plurality of LEDs is associated with a lens that is locatedforward of its associated LED, a diffuser is located forward of each LEDand close to each LED, so that each LED produces an illuminated spot onthe diffuser, the lens associated with each LED in the plurality of LEDsforms a beam by projecting an image of the illuminated spot on thediffuser, and wherein all of the said lenses associated with LEDs in theplurality of LEDs form beams that merge together to form a usefulcombined beam.
 20. The LED work light of claim 19, wherein the LEDsinclude at least one white LED, at least one red LED, and at least onegreen LED.
 21. The LED work light of claim 1, wherein the LEDs arediffused LEDs.
 22. The LED work light of claim 21, wherein the diffusedLEDs have flat forward surfaces.
 23. The LED work light of claim 22,wherein the LEDs include at least one white LED, at least one red LED,and at least one green LED.
 24. An LED work light comprising: a handlesection and a head section, and a plurality of LEDs mounted in the headsection, and means for the plurality of LEDs to receive electricalpower, wherein: each LED within the plurality of LEDs is associated witha lens that is located forward of its associated LED, wherein each LEDhas chips located substantially rearward of the forward surface of eachLED, wherein each lens forms a beam of width 40 to 90 degrees wide, andwherein the beams merge together into a single beam that is 40 to 90degrees wide.
 25. The LED work light of claim 9, further having a lensforward of each LED to form the light from the LEDs into a beam that is40 to 90 degrees wide.
 26. The LED work light of claim 26, wherein theLEDs have chips located substantially rearward of the edges of the frontsurfaces of the LEDs.